PE19.1-17 | Neonatology — Glossary

The neonatal compression-to-ventilation ratio: three compressions followed by one ventilation breath, yielding 90 compressions and 30 ventilations per minute; differs from the adult 30:2 ratio because neonatal arrest is hypoxic.

Haemolytic disease of the newborn caused by maternal anti-A or anti-B IgG antibodies crossing the placenta; occurs when the mother is blood group O and the infant is group A or B; usually milder than Rh disease but the commonest cause of day-1 jaundice.

The standard antiviral treatment for neonatal HSV encephalitis and disseminated disease; dose 60 mg/kg/day IV in 3 divided doses; duration 14 days for SEM disease and 21 days for CNS/disseminated disease; empirical therapy is started for any neonate with vesicles or encephalitis pending HSV PCR.

A severe, rapidly progressive form of ROP characterised by Zone I or posterior Zone II location, extensive plus disease (dilated, tortuous vessels in all four quadrants), and absence of sequential staging — rapidly progresses to Stage 4–5 without the usual Stage 1–2–3 progression; requires urgent treatment.

Radiographic sign seen when patent central airways are visible against a background of collapsed or consolidated alveoli; characteristic of RDS, pneumonia, and atelectasis — the airway is patent but the surrounding parenchyma is not aerated.

A bedside monitoring tool that continuously records and displays background cerebral electrical activity in a compressed format; used in the NICU to classify HIE severity, monitor treatment response, and detect subclinical seizures.

A spectrum of congenital defects in which the anus and rectum fail to form normally; classified as low (below levator ani, perineal fistula, good prognosis) or high (supralevator, no visible anal opening, associated sacral and genitourinary anomalies).

Betamethasone (2 × 12 mg IM 24 h apart) or dexamethasone (4 × 6 mg IM 12 h apart) given to mothers at risk of preterm delivery at 24–34 weeks; accelerates fetal lung maturity and reduces RDS, IVH, and NEC.

Intravitreal injection of bevacizumab (0.625 mg) to block VEGF-driven neovascularisation in Type 1 ROP; particularly effective for Zone I and aggressive posterior ROP; allows retinal vascular development to complete but requires long-term ophthalmology follow-up for late reactivation.

A five-parameter clinical scoring system (HR, respiration, muscle tone, reflex irritability, colour; 0–2 each) applied at 1 and 5 minutes after birth to assess the neonate's immediate condition and guide resuscitation decisions.

Respiratory pauses >20 seconds (or shorter with bradycardia/desaturation) in preterm neonates due to brainstem respiratory control immaturity; treated with caffeine citrate (methylxanthine) which stimulates respiratory centres.

Alkali denaturation test distinguishing fetal haemoglobin (HbF, alkali-resistant — blood stays pink) from maternal haemoglobin (HbA, denatures to yellow-green) in neonatal haematemesis; used to diagnose swallowed maternal blood as a benign cause of early GI bleeding.

IUGR pattern in which head circumference is relatively preserved (brain-sparing) while body weight and abdominal circumference (liver) are reduced; caused by late-onset placental insufficiency; presents with a thin 'alert' infant and high hypoglycaemia risk.

The New Ballard Score estimates gestational age by assessing six neuromuscular and six physical maturity criteria; used when gestational age is uncertain from menstrual/ultrasound data.

The developmental origins of adult disease concept: fetal undernutrition programs metabolic systems towards insulin resistance and fat conservation, leading to increased adult risk of hypertension, type 2 diabetes, and coronary artery disease when exposed to adequate postnatal nutrition.

The amount of base (in mmol/L) required to titrate 1 litre of blood to pH 7.4 at 37°C and normal PaCO₂; base deficit >12 mmol/L in cord blood indicates significant metabolic acidosis consistent with birth asphyxia.

An overgrowth syndrome characterised by macrosomia, macroglossia, omphalocele, and hyperinsulinism (due to β-cell hyperplasia); a cause of persistent neonatal hypoglycemia requiring diazoxide treatment.

An hour-specific bilirubin nomogram for term and near-term neonates (≥35 weeks) that assigns risk zones (low/low-intermediate/high-intermediate/high) for predicting subsequent severe hyperbilirubinaemia; used to guide phototherapy and exchange transfusion thresholds.

A progressive obliteration of the extrahepatic bile ducts leading to cholestatic jaundice, pale stools, and malabsorption of fat-soluble vitamins; the most important underlying condition associated with late VKDB; treated with Kasai portoenterostomy.

Vomiting that is green or yellow in colour due to the presence of bile; in neonates, bile-stained vomiting indicates obstruction distal to the ampulla of Vater and is always a surgical emergency until proven otherwise.

A spectrum of neurological injury from unconjugated bilirubin toxicity graded 1 (subtle — high-pitched cry, hypotonia) through 2 (moderate — opisthotonus, fever) to 3 (severe acute encephalopathy); clinical staging used when bilirubin level alone is insufficient to guide urgency.

Failure of adequate gas exchange at or around the time of birth, causing hypoxia, hypercarbia, and metabolic acidosis; diagnosed clinically by persistent low APGAR plus cord blood pH <7.0 or base deficit >12 mmol/L.

Birth weight >4 kg (or >90th percentile for gestational age); associated with increased risk of shoulder dystocia, brachial plexus injury, clavicle fracture, and subgaleal haemorrhage.

The gold standard diagnostic test for neonatal sepsis; requires at least 1 mL blood in an aerobic bottle; sensitivity 30–40% in clinical sepsis; must be drawn before the first antibiotic dose but must not delay antibiotic therapy in a sick neonate.

Neonatal peripheral nerve injury to the brachial plexus (C5–T1) resulting from traction during delivery; most commonly associated with shoulder dystocia.

The fetal adaptive response to placental insufficiency in which blood flow is preferentially redistributed to the brain and heart at the expense of the liver, gut, and extremities; the mechanism underlying asymmetric IUGR and the reason SGA infants have relatively large heads but depleted liver glycogen stores.

Chronic lung disease of prematurity defined as requirement for supplemental oxygen or respiratory support at 36 weeks corrected gestational age; caused by oxygen toxicity, barotrauma, and inflammation in immature lungs; results in simplified alveolar architecture, pulmonary fibrosis, and pulmonary hypertension.

A specialised form of fat tissue, rich in mitochondria and uncoupling protein (UCP-1), that generates heat through non-shivering thermogenesis; the primary mechanism of neonatal heat production, located in the nape, interscapular, and perirenal areas.

A methylxanthine medication (loading 20 mg/kg IV/PO, then 5 mg/kg/day) used as first-line treatment for apnoea of prematurity; stimulates the respiratory centre, improves respiratory muscle contractility; evidence shows reduction in apnoea, extubation failure, and bronchopulmonary dysplasia (CAP trial).

The active form of vitamin D; produced by renal 1α-hydroxylation under PTH stimulation; increases intestinal calcium absorption; used therapeutically in hypoparathyroidism (bypasses the PTH-dependent activation step).

The standard IV preparation for treating symptomatic neonatal hypocalcemia; contains 9.3 mg elemental calcium per mL; given at 1–2 mL/kg over 10–30 minutes with continuous ECG monitoring; preferred over calcium chloride due to lower tissue irritancy.

Diffuse oedematous swelling of the scalp soft tissue that crosses suture lines, resulting from pressure during vaginal delivery; resolves within 24–48 hours and requires no treatment.

Subperiosteal collection of blood that does not cross suture lines, caused by shear forces during delivery; resolves over weeks to months; associated with risk of neonatal jaundice due to reabsorption.

Jaundice caused by impaired bile flow leading to accumulation of conjugated bilirubin; characterised by pale/acholic stools, dark urine, and malabsorption of fat-soluble vitamins (A, D, E, K); an important risk factor for late VKDB.

Facial muscle twitching elicited by tapping the facial nerve anterior to the ear; a sign of neuromuscular hyperexcitability in hypocalcemia; positive in 10–25% of normal neonates, limiting its specificity.

VKDB presenting on days 2–7 of life in exclusively breastfed neonates who did not receive Vitamin K prophylaxis; most common form; umbilical and GI bleeding typical; infant is otherwise well.

Congenital orofacial clefts resulting from failure of fusion of the facial processes; cleft lip (with or without palate) results from failure of fusion of the medial nasal and maxillary processes; isolated cleft palate from failure of palatal shelf fusion; creates feeding difficulties and airway risk in the newborn period.

A group of commensal skin staphylococci (principally S. epidermidis) that are the most common cause of late-onset nosocomial sepsis in NICU-admitted neonates; pathogenic primarily through biofilm formation on indwelling devices; treated with vancomycin.

The metabolic response of a neonate to environmental cooling, triggering BAT activation, increased oxygen consumption, glucose depletion, and — if prolonged — metabolic acidosis, pulmonary vasoconstriction, and hypoxia; can occur even before temperature falls below normal threshold.

The first breast milk secreted from days 1–5 postpartum; thick, yellowish, low in volume but rich in secretory IgA, lactoferrin, and growth factors that prime the neonatal immune system and gut.

The most common congenital infection worldwide; caused by cytomegalovirus; 10% symptomatic at birth (IUGR, microcephaly, periventricular calcifications, petechiae, hepatosplenomegaly); treated with valganciclovir for 6 months; most important non-hereditary cause of sensorineural hearing loss.

A defect in the diaphragm (most commonly left-sided Bochdalek type) through which abdominal organs herniate into the thorax, compressing the developing lung and causing pulmonary hypoplasia and neonatal pulmonary hypertension.

A genetic disorder (most commonly KATP channel mutations in SUR1/Kir6.2) causing unregulated pancreatic insulin release; presents with recurrent severe hypoglycemia from the newborn period onward.

Neonatal infection with Treponema pallidum, acquired transplacentally; classic features include snuffles (nasal discharge), hepatosplenomegaly, periostitis on X-ray, saddle nose deformity, and rash; treated with aqueous penicillin G IV for 10 days.

Water-soluble bilirubin conjugated with glucuronic acid in the liver; a level >1 mg/dL (or >20% of total serum bilirubin) is always pathological and indicates hepatobiliary disease or metabolic disorder.

An obstetric emergency in which the umbilical cord descends below the presenting fetal part, causing compression of the cord by the fetal head against the maternal pelvis and complete interruption of umbilical blood flow.

The age of a preterm infant calculated from the original expected date of delivery rather than the actual birth date; used for developmental and medical milestones in preterm infants; 36 weeks CGA is the key benchmark for BPD diagnosis.

An estimate of true serum calcium adjusted for hypoalbuminaemia using the formula: corrected Ca = measured Ca (mg/dL) + 0.8 × [4 − albumin (g/dL)]; useful when ionised calcium cannot be measured directly but less reliable than ionised calcium.

Continuous positive airway pressure delivered via nasal prongs to a spontaneously breathing preterm neonate with respiratory distress; pressure 5–8 cm H₂O; maintains alveolar patency and reduces work of breathing.

A set of blood tests (insulin, C-peptide, cortisol, GH, glucagon, FFAs, ketones, lactate, ammonia) drawn simultaneously at the time of documented hypoglycemia to identify the underlying hormonal or metabolic aetiology.

Fever in the first week of life in breastfed neonates caused by inadequate milk intake leading to hypernatraemic dehydration; associated with weight loss >10%, sunken fontanelle, concentrated urine; managed with hydration (frequent breastfeeding ± supplemental expressed milk); must be distinguished from infectious fever.

Clamping the umbilical cord 60–180 seconds after birth (rather than immediately); allows transfusion of 25–40 mL of placental blood to the neonate, improving iron stores and reducing neonatal anaemia.

A thin, flat white line on the retinal surface at the boundary between vascularised and avascular retina; the earliest ophthalmoscopic sign of ROP; occurs in the avascular zone and may regress spontaneously.

A fracture in which the broken skull fragment is displaced inward below the level of the surrounding bone; in neonates, often caused by pressure from forceps or the bony maternal pelvis.

A potassium-channel (KATP) opener used for medical management of hyperinsulinism; dose 5–15 mg/kg/day in 2–3 divided doses; first-line pharmacotherapy before considering partial pancreatectomy.

Pathological activation of coagulation causing both thrombosis and haemorrhage; characterised by prolonged PT and aPTT, low platelet count, low fibrinogen, elevated D-dimers, and a sick infant with a triggering illness; distinguished from VKDB by thrombocytopenia and clinical context.

A chromosomal microdeletion syndrome (22q11.2 deletion) characterised by parathyroid aplasia/hypoplasia (permanent hypoparathyroidism), thymic aplasia (T-cell immunodeficiency), conotruncal cardiac defects, and characteristic facies; causes persistent neonatal hypocalcemia requiring lifelong calcitriol and calcium.

A laboratory test that detects antibodies or complement proteins bound to the surface of red blood cells; positive in Rh and ABO haemolytic disease of the newborn, confirming immune-mediated haemolysis.

Radiological appearance on plain abdominal X-ray of two gas-filled structures (stomach and dilated proximal duodenum) separated by the pylorus, with no distal gas; pathognomonic of duodenal atresia.

A fetal shunt connecting the pulmonary artery to the descending aorta, allowing blood to bypass the fluid-filled lungs; normally closes within 24–48 hours of birth in response to rising oxygen tension and falling prostaglandins.

A two-handed mask-holding technique where the thumb and index finger form a 'C' around the mask while the remaining fingers form an 'E' lifting the jaw; maintains mask seal while supporting the airway.

VKDB presenting within 24 hours of birth, almost always caused by maternal use of Vitamin K-antagonising drugs (warfarin, phenytoin, phenobarbitone, rifampicin, isoniazid); high risk of intracranial haemorrhage.

Neonatal hypocalcemia presenting within the first 72 hours of life; associated with prematurity, IDM, perinatal asphyxia; mechanism is transient parathyroid gland immaturity or suppression plus elevated neonatal calcitonin.

Neonatal sepsis presenting within the first 72 hours of life; caused by vertically transmitted organisms from the maternal genital tract; key pathogens include GBS, E. coli, Listeria, and Klebsiella; risk factors include prolonged ROM >18 hours and chorioamnionitis.

The dissociation between clinical seizure movements and EEG activity in neonates; may occur when clinical movements are subcortical automatisms without cortical EEG correlate, or when AEDs suppress clinical manifestations but leave electrographic seizures running.

The reabsorption of unconjugated bilirubin formed in the gut (via β-glucuronidase deconjugation) back into the portal circulation; enhanced in neonates by immature gut flora and reduced meconium clearance, increasing the bilirubin load on the liver.

Emergency cardiac drug used in neonatal resuscitation when HR <60 despite CPR; dose 0.1–0.3 mL/kg of 1:10,000 solution IV via umbilical venous catheter (or 0.5–1.0 mL/kg via ETT if IV unavailable).

Brachial plexus birth palsy affecting C5 and C6 nerve roots, causing the classic waiter's tip posture (shoulder adduction, elbow extension, forearm pronation, wrist flexion) with preserved hand grasp.

A benign, self-limiting neonatal rash appearing days 1–3, characterised by erythematous macules and papules with white or yellow centres; requires no treatment and resolves within 1–2 weeks.

Heat lost through evaporation of liquid (amniotic fluid or sweat) from the skin surface; the dominant mechanism of heat loss in the immediate post-delivery period; prevented by immediate drying with a warm towel.

A double-volume procedure (~160–180 mL/kg) that removes sensitised red cells, free bilirubin, and maternal antibodies, replacing them with compatible donor blood; the definitive treatment for severe neonatal haemolytic disease when phototherapy is inadequate.

Neuronal death caused by excessive glutamate-mediated activation of NMDA/AMPA receptors, leading to sustained calcium influx, mitochondrial calcium overload, and activation of destructive enzymes; a key mechanism in HIE secondary injury.

Feeding the infant only breast milk (no water, other liquids, or foods except permitted medicines) for the first 6 months of life; the most effective single intervention for reducing infant mortality in low-income settings.

Animal-derived (bovine or porcine) surfactant preparation administered via endotracheal tube to replace deficient endogenous surfactant in RDS; examples include beractant (100 mg/kg) and poractant alfa (200 mg/kg first dose).

Breast milk expressed manually or with a pump for feeding preterm or LBW infants who cannot latch; reduces NEC, improves gut colonisation with beneficial bacteria, provides IgA and growth factors; the gold standard nutrition for all LBW infants.

A sex-specific preterm growth reference chart plotting weight, length, and head circumference by gestational age (22–50 weeks); the standard tool for identifying SGA and monitoring growth velocity in preterm and LBW neonates.

Rhythmic jerking (1–3 per second) confined to one limb or one side of the face; usually has an EEG correlate; most commonly caused by focal cortical injury (arterial infarction, focal haemorrhage).

A fetal right-to-left atrial shunt that allows oxygenated blood from the inferior vena cava to bypass the pulmonary circulation; closes functionally within minutes of birth as pulmonary vascular resistance falls.

A blood product containing all coagulation factors; used in VKDB for immediate replacement of clotting factors in life-threatening haemorrhage, at a dose of 10–15 mL/kg, while waiting for Vitamin K to take effect.

X-linked recessive enzyme deficiency causing episodes of oxidative haemolysis triggered by infection, drugs (primaquine, dapsone, nitrofurantoin), naphthalene balls, and fava beans; the most common enzyme deficiency causing neonatal jaundice in India.

The flat tendinous sheet forming the middle layer of the scalp, connecting the frontalis muscle anteriorly and occipitalis posteriorly; the subgaleal space lies deep to it and is continuous across the entire scalp.

Post-translational modification of glutamic acid residues on Vitamin K-dependent clotting factors by Vitamin K-dependent carboxylase; creates calcium-binding sites required for coagulant activity.

A full-thickness abdominal wall defect to the right of the umbilicus with no covering sac; the herniated bowel is directly exposed to amniotic fluid, causing chemical peritonitis (peel); typically an isolated anomaly not associated with chromosomal syndromes.

Synthesis of glucose from non-carbohydrate precursors (lactate, glycerol, amino acids) in the liver; sustains blood glucose during prolonged fasting, but is immature in preterm neonates.

The rate of glucose delivery expressed in mg/kg/min; calculated as [dextrose % × infusion rate mL/hr] ÷ [6 × weight kg]; standard starting GIR for neonatal hypoglycemia is 6–8 mg/kg/min.

The enzymatic breakdown of stored hepatic glycogen to glucose-1-phosphate, and then to free glucose for release into the bloodstream; the primary rapid source of glucose during fasting.

The first 60 seconds after birth, targeted by the HBB/NRP programme as the window within which initial stabilisation steps must be completed and the need for PPV assessed.

Incomplete fracture in which one cortex is broken while the other is bent but intact, occurring more commonly in the flexible bones of infants and young children.

A radiographic finding of diffuse haze that does not obscure the underlying vascular markings, caused by partial alveolar collapse or filling; the hallmark chest X-ray pattern of RDS in preterm neonates.

Streptococcus agalactiae; the leading cause of EOS in developed countries; colonises the maternal genital tract in 15–30% of women; transmitted vertically at birth; causes pneumonia, bacteraemia, and meningitis in neonates; covered by ampicillin.

A low-pitched sound produced by partial glottic closure during expiration, generating intrinsic PEEP to prevent alveolar collapse; a sign of significant respiratory distress and scored as 2 in the Silverman-Anderson scale.

X-linked recessive deficiency of Factor VIII; presents with prolonged aPTT and normal PT (Factor VIII is in the intrinsic pathway only); affects males predominantly; distinguished from VKDB by the normal PT and sex of the patient.

WHO/AAP neonatal resuscitation training programme adapted for low-resource settings; India's primary education tool for skilled birth attendants; emphasises the golden minute and bag-mask ventilation.

Congenital aganglionosis of the distal bowel due to failure of neural crest cell migration; the aganglionic segment (always including the rectum) is tonically contracted, preventing peristalsis and causing progressive proximal dilatation.

Standard method for calculating daily maintenance fluid requirements in children: 100 mL/kg/day for the first 10 kg, plus 50 mL/kg/day for the next 10 kg, plus 20 mL/kg/day for each additional kg.

An NHM India programme in which trained ASHAs make scheduled postnatal home visits (days 1, 3, 7, 14, 21, 28) to monitor the neonate, support breastfeeding, and detect warning signs early in community settings.

Ipsilateral ptosis, miosis, and anhidrosis caused by interruption of the sympathetic pathway; in neonates, a feature of Klumpke palsy (T1 involvement).

Inappropriately elevated insulin secretion in the context of hypoglycemia, causing excessive glucose uptake and suppression of counter-regulatory ketogenesis; the most common cause of persistent neonatal hypoglycemia.

Administration of 100% oxygen for 10 minutes with measurement of PaO₂; PaO₂ >150 mmHg suggests pulmonary disease (oxygenation improves with oxygen); PaO₂ <150 mmHg suggests cyanotic congenital heart disease with obligatory right-to-left shunting.

Serum magnesium below 0.6 mmol/L; impairs PTH secretion and PTH receptor signalling, causing refractory hypocalcemia; corrected with magnesium sulphate 50% 0.2 mL/kg IM before or alongside calcium therapy.

Brain injury resulting from birth asphyxia, manifesting as a spectrum of neurological signs from mild encephalopathy (Sarnat I) to coma (Sarnat III); the most important cause of neonatal seizures and cerebral palsy.

Immature-to-total neutrophil ratio; the proportion of band (immature) neutrophils relative to total neutrophil count; a value >0.2 indicates bone marrow stress from infection; one of the five NNF sepsis screen criteria.

A neonate born to a mother with gestational or pre-existing diabetes; at risk of transient hyperinsulinism, macrosomia, hypoglycemia within the first few hours of life, and other metabolic complications.

A selective pulmonary vasodilator administered by inhalation at 20 ppm; used for persistent pulmonary hypertension of the newborn (PPHN), especially complicating MAS; acts on pulmonary vascular smooth muscle without systemic hypotensive effects.

INtubate–SURfactant–Extubate: administration of endotracheal surfactant followed by rapid extubation back to CPAP; minimises mechanical ventilation exposure in preterm neonates with RDS.

Phototherapy delivering ≥30 µW/cm²/nm over maximum skin surface area; used when bilirubin is within 2–3 mg/dL of the exchange transfusion threshold or is rapidly rising.

Administration of IV penicillin or ampicillin to GBS-colonised mothers during labour; reduces neonatal EOS from GBS by 70–80%; the key prevention strategy for GBS EOS in developed countries; recommended in mothers with known GBS vaginal colonisation.

High-dose IgG preparation given at 0.5–1 g/kg IV to reduce ongoing haemolysis in confirmed ABO or Rh haemolytic disease by blocking Fc receptors on phagocytes; used as adjunct to intensive phototherapy to reduce the need for exchange transfusion.

Bleeding into the germinal matrix and lateral ventricles in preterm neonates; classified Grades I–IV (Papile); caused by fragility of germinal-matrix vasculature and fluctuations in cerebral blood flow; detected by cranial ultrasound.

The free, unbound fraction of serum calcium (~50% of total); the physiologically active form that regulates neuromuscular excitability and cardiac contractility; measured directly by ion-selective electrode on a blood gas analyser.

Pathological process in which the fetus fails to achieve its growth potential due to fetal, placental, or maternal factors; detected antenally by serial biometry and Doppler or postnally as SGA.

Continuous skin-to-skin contact of a stable newborn (especially LBW/preterm) with the mother's chest; improves thermoregulation, breastfeeding success, neurodevelopmental outcome, and reduces mortality; WHO-recommended as superior to incubator care for stable neonates.

Permanent neurological damage from bilirubin deposition in the basal ganglia and brainstem nuclei, presenting chronically as athetoid cerebral palsy, sensorineural hearing loss, dental enamel dysplasia, and upward gaze palsy.

Brachial plexus birth palsy affecting C8 and T1 nerve roots, producing claw-hand deformity and, when T1 is involved, ipsilateral Horner syndrome (ptosis, miosis, anhidrosis).

A clinical method correlating the cephalocaudal progression of jaundice in neonates with estimated serum bilirubin levels, from zone 1 (face, ~5 mg/dL) to zone 5 (palms and soles, >15 mg/dL).

The surgical operation for malrotation (with or without volvulus): detorsion of the volvulus, division of Ladd's bands, broadening of the mesenteric root, appendicectomy (to avoid future confusion), and positioning the colon on the left and the small bowel on the right.

Inability to close the eyelid completely; seen in peripheral facial nerve palsy and requires eye protection (artificial tears, patching) to prevent corneal exposure injury.

Sudden spasm of the vocal cords causing stridor and acute cyanosis; a rare but immediately life-threatening manifestation of severe hypocalcemia in the neonate.

Thermal ablation of the avascular peripheral retina using laser energy, eliminating the source of the pathological VEGF surge; the established treatment for Type 1 ROP; performed under sedation or general anaesthesia with indirect ophthalmoscopy.

VKDB presenting from 2 weeks to 6 months of age in exclusively breastfed infants without prophylaxis, or in infants with fat-soluble vitamin malabsorption (biliary atresia, cholestatic liver disease); carries 30–60% risk of intracranial haemorrhage.

Neonatal hypocalcemia presenting after 72 hours (typically days 5–10); most commonly caused by phosphate overload from high-phosphate cow's milk formula, but also vitamin D deficiency, hypomagnesaemia, or DiGeorge syndrome.

Neonatal sepsis presenting after 72 hours; predominantly nosocomial in hospitalised neonates; key pathogens include CoNS, Staphylococcus aureus, Klebsiella, and Candida; risk factors include prematurity, indwelling devices, and prolonged antibiotic exposure.

The window of approximately 6 hours between primary and secondary energy failure, during which the brain has partially recovered and therapeutic hypothermia can interrupt the secondary injury cascade.

Second-line AED for neonatal seizures (40–60 mg/kg IV); acts via SV2A synaptic vesicle protein; increasingly used due to favourable safety profile (less respiratory depression than phenobarbitone) and lack of drug interactions.

Birth weight below 2,500 g regardless of gestational age; associated with increased risk of hypothermia, hypoglycaemia, infection, and long-term developmental impairment.

The predominant water-soluble photoproduct of phototherapy, formed from unconjugated bilirubin by structural photo-isomerisation; excreted directly in bile without hepatic conjugation, accounting for the rapid response to intensive phototherapy.

The standard preparation for IM magnesium replacement in neonatal hypomagnesaemia; given at 0.2 mL/kg IM (= 0.1 mmol/kg elemental magnesium); corrects PTH-resistant hypocalcemia by restoring the magnesium cofactor for PTH secretion.

Failure of the midgut to complete its 270° counter-clockwise rotation during fetal development, resulting in an abnormally positioned caecum and a narrow mesenteric root that predisposes to midgut volvulus.

Respiratory distress caused by aspiration of meconium-stained amniotic fluid in utero or at delivery; involves airway obstruction, chemical pneumonitis, surfactant inactivation, and pulmonary hypertension in severe cases.

Intestinal obstruction in the newborn caused by inspissated (thickened) meconium impacted in the terminal ileum; the neonatal manifestation of cystic fibrosis in approximately 10–15% of CF patients; presents with failure to pass meconium and abdominal distension.

Amniotic fluid discoloured green or black by fetal meconium; indicates possible in utero hypoxia; management depends on whether the neonate is vigorous (routine care) or non-vigorous (consider airway suctioning).

Twisting of the entire midgut around the superior mesenteric artery axis due to malrotation, causing intestinal ischaemia that can progress to infarction of the small bowel and right colon within 4–6 hours; a neonatal surgical emergency.

Axillary temperature 36.0–36.4°C in a neonate (WHO classification); managed with extra clothing, skin-to-skin contact, and breastfeeding; requires close monitoring.

A small-volume, rapid IV glucose correction dose: 10% dextrose 2 mL/kg (= 200 mg/kg) given over 5 minutes; the standard neonatal emergency glucose bolus, avoiding the rebound risk of 50% dextrose.

Axillary temperature 32.0–35.9°C in a neonate; managed with active rewarming (KMC or radiant warmer) at 0.5°C/hour, blood glucose monitoring, and glucose supplementation if needed.

A primitive neonatal reflex elicited by a sudden movement of the head — the infant symmetrically extends then flexes the arms with a brief cry; normally present from birth to 4 months; its absence or asymmetry may indicate neurological injury.

The corrective sequence for ineffective PPV: Mask adjustment, Reposition airway, Suction, Open mouth, Pressure increase, Airway alternative (LMA/ETT).

Systemic injury accompanying HIE: acute kidney injury, hepatic dysfunction (raised transaminases), cardiomyopathy, NEC, coagulopathy/DIC, and adrenal haemorrhage; portends a worse prognosis and requires multi-system monitoring.

India's official schedule for routine childhood immunisation, updated periodically by the Ministry of Health & Family Welfare; at birth it includes BCG (intradermal), OPV-0 (oral), and Hepatitis B birth dose (IM).

Severe intestinal inflammation and necrosis in preterm neonates, typically presenting at 2–3 weeks with abdominal distension, bloody stools, and haemodynamic instability; associated with pneumatosis intestinalis on X-ray; managed with bowel rest, antibiotics, and surgery if perforation occurs.

Elevation of total serum bilirubin above normal for age in a newborn, most commonly due to increased production (haemolysis or polycythaemia), decreased hepatic conjugation, or increased enterohepatic reabsorption.

Total serum calcium below 7.5 mg/dL in term neonates (or below 7.0 mg/dL in preterm), or ionised calcium below 1.0 mmol/L; the ionised fraction is the physiologically relevant measurement.

Blood glucose below 45 mg/dL in a neonate (whole blood glucometer); the operational treatment threshold recommended by the NNF India and the AAP.

The first 28 days of life; subdivided into early neonatal (0–7 days) and late neonatal (8–28 days); carries the highest mortality risk of any age interval.

Systemic infection occurring in the first 28 days of life, presenting with non-specific signs (poor feeding, temperature instability, respiratory distress, lethargy); classified as early-onset (<72 hours) or late-onset (>72 hours) based on timing and organism source.

The mildest grade of nerve injury involving temporary conduction block without axonal disruption; complete recovery is expected. The most common type in brachial plexus birth palsy.

The ambient temperature range at which a neonate's oxygen consumption and glucose utilisation are minimised; approximately 32–34°C for term neonates, 34–36°C for preterm neonates <1,500 g.

Absolute neutrophil count <1,500/µL in a neonate; a marker of severe infection (bone marrow neutrophil storage pool exhausted) or congenital bone marrow suppression; in the context of clinical sepsis, neutropenia worsens prognosis significantly.

Neuronal chloride cotransporters: NKCC1 (Na-K-2Cl cotransporter) imports chloride into cells; KCC2 (K-Cl cotransporter) exports it. In neonates, NKCC1 predominates, keeping intracellular chloride high — causing GABA-A channel opening to be depolarising (excitatory) rather than hyperpolarising.

Heat generation by oxidation of triglycerides in brown adipose tissue (BAT), the primary mechanism for cold defence in neonates who cannot shiver effectively; increases glucose and oxygen consumption.

Heat production without skeletal muscle contractions; achieved in neonates via BAT activation (catecholamines → beta-3 adrenergic receptors → lipolysis → fatty acid oxidation → UCP1 uncoupling → heat); the dominant thermogenic mechanism in neonates.

A somatostatin analogue that suppresses insulin secretion; used in diazoxide-unresponsive congenital hyperinsulinism at doses of 5–20 µg/kg/day.

Congenital interruption of the oesophageal lumen with the proximal segment ending in a blind pouch; prevents swallowing of secretions and oral feeds; presents as drooling, choking, and cyanosis on first feed.

A midline abdominal wall defect at the base of the umbilical cord covered by a membrane (peritoneum and amnion); may contain bowel, liver, and spleen; associated with chromosomal anomalies (trisomy 13/18/21) and Beckwith-Wiedemann syndrome.

Neonatal conjunctivitis, most critically caused by Neisseria gonorrhoeae or Chlamydia trachomatis acquired during passage through an infected birth canal; prevented by tetracycline 1% eye ointment at birth.

Tissue damage caused by supraphysiological concentrations of oxygen, mediated by reactive oxygen species (superoxide, hydrogen peroxide, hydroxyl radical) that cause lipid peroxidation, DNA damage, and cell death, particularly in organs with immature antioxidant defences.

The principal regulator of serum calcium; raises calcium by stimulating bone resorption, renal calcium reabsorption, and 1α-hydroxylation of vitamin D; secreted by chief cells of the parathyroid glands; requires magnesium as a cofactor for secretion.

Reduction of body temperature by removing heat sources (blankets, radiant warmer) and exposing the neonate to room air; used as a bridge during transport to a cooling-capable centre when servo-controlled equipment is unavailable.

Jaundice appearing within the first 24 hours of birth, or persisting beyond day 14 in a term neonate, or with signs of haemolysis/direct bilirubin elevation; requires urgent investigation for haemolytic disease, sepsis, or metabolic cause.

Focal infarction in the territory of a cerebral artery (most commonly the left middle cerebral artery) occurring in the perinatal period; presents with unilateral (focal) clonic seizures in an otherwise well term neonate; the leading cause of hemiplegia.

Also called persistent pulmonary hypertension of the newborn (PPHN); failure of the normal postnatal fall in pulmonary vascular resistance, causing right-to-left shunting and severe hypoxia unresponsive to conventional oxygen therapy.

Failure of the normal postnatal fall in pulmonary vascular resistance, maintaining right-to-left shunting through the foramen ovale and ductus arteriosus; causes severe hypoxaemia disproportionate to the degree of lung disease; common complication of MAS.

First-line antiepileptic drug for neonatal seizures; loading dose 20 mg/kg IV over 15–30 minutes (maximum 40 mg/kg); acts by potentiating GABA-A and antagonising NMDA receptors; monitor for respiratory depression and hypotension.

The first-line anticonvulsant for neonatal seizures; loading dose 20 mg/kg IV slow infusion over 30 minutes; mechanism: GABA-A receptor potentiation.

Second-line AED for neonatal seizures after phenobarbitone failure; loading dose 20 mg/kg IV at ≤1 mg/kg/min; acts by blocking voltage-gated sodium channels; monitor ECG continuously during infusion due to risk of arrhythmia and hypotension.

The principal mechanism of late-onset neonatal hypocalcemia when cow's milk is used; cow's milk contains ~6× the phosphate of breast milk; the immature neonatal kidney cannot excrete excess phosphate, causing serum phosphate to rise and ionised calcium to fall by calcium-phosphate complexation.

Treatment using blue-spectrum light to convert unconjugated bilirubin in skin capillaries into more water-soluble isomers that can be excreted without conjugation; used for neonatal hyperbilirubinaemia including that caused by cephalhaematoma.

Unconjugated hyperbilirubinaemia appearing after 24 hours of birth in a term, well neonate due to haemolysis of fetal haemoglobin and immature hepatic conjugation capacity; peaks day 3–5 and resolves by day 10–14.

Proteins Induced by Vitamin K Absence or Antagonism — functionally inactive Vitamin K-dependent clotting factors that are synthesised by the liver but cannot be activated without gamma-carboxylation; elevated levels are a sensitive marker of Vitamin K deficiency.

Dilatation and tortuosity of the posterior retinal vessels in at least two quadrants on ophthalmoscopy; indicates active, aggressive ROP and upstages disease severity; its presence converts Type 2 ROP to Type 1 (treatment threshold) at Stage 2–3 Zone II.

Haematocrit above 65% in a neonate; excess erythrocytes have high glucose consumption, contributing to hypoglycemia; treated with partial-exchange transfusion if symptomatic.

Active inflation of the neonatal lungs using a bag-mask device at 40–60 breaths/min; the primary resuscitative intervention when the neonate fails to breathe or has HR <100 bpm after initial steps.

Birth before 37 completed weeks of gestation; subcategorised as late preterm (34–36+6 weeks), moderate preterm (32–33+6 weeks), very preterm (<32 weeks), and extremely preterm (<28 weeks).

The initial cessation of breathing in a hypoxic neonate, during which the heart rate is still adequate and stimulation alone (drying, rubbing) can restore breathing.

The initial phase of HIE during the asphyxic insult, characterised by ATP depletion, membrane depolarisation, cytotoxic oedema, and necrotic cell death from failure of the Na⁺/K⁺-ATPase pump.

A blood product containing concentrated Vitamin K-dependent factors (II, VII, IX, X) and proteins C and S; provides rapid coagulation factor replacement in life-threatening haemorrhage; used as an alternative to FFP when volume overload is a concern.

A coagulation test measuring the time for clot formation via the extrinsic and common pathways (Factors I, II, V, VII, X); prolonged in VKDB due to deficiency of Vitamin K-dependent factors II, VII, and X.

Apparent paralysis of a limb in a neonate caused by pain from a fracture or injury rather than true nerve or muscle dysfunction; the infant avoids moving the limb voluntarily.

Elevated pulmonary artery pressure resulting from hypoxic pulmonary vasoconstriction, vascular remodelling, and reduced vascular bed in BPD; detected by echocardiography; treated with sildenafil (phosphodiesterase-5 inhibitor) and inhaled nitric oxide in acute severe cases.

Reduced lung development with fewer airway generations and smaller vascular bed, resulting from prolonged in-utero compression of the developing lung by herniated abdominal organs in CDH; determines survival more than hernia size.

A rare autosomal recessive disorder (ALDH7A1 mutation) causing refractory neonatal seizures unresponsive to standard AEDs; the diagnostic trial is IV pyridoxine 100 mg, which terminates seizures within minutes; lifelong pyridoxine supplementation is then required.

Lengthening of the corrected QT interval beyond 0.45 seconds on ECG; a key non-invasive indicator of hypocalcemia, reflecting delayed ventricular repolarisation; shortens with hypercalcaemia.

Chemically reactive molecules derived from molecular oxygen, including superoxide (O₂⁻), hydrogen peroxide (H₂O₂), and hydroxyl radical (•OH); generated as by-products of oxidative metabolism and in excess during hyperoxia; neutralised by antioxidant enzymes (SOD, catalase, glutathione peroxidase).

A double-lumen sump nasogastric catheter placed in the upper oesophageal pouch of a TOF/OA patient and connected to continuous low-pressure suction to prevent aspiration of pooled secretions.

A condition of preterm neonates caused by surfactant deficiency, leading to alveolar collapse at end-expiration, diffuse bilateral ground-glass X-ray opacification, and progressive respiratory failure; treated with CPAP and exogenous surfactant.

Pathological retinal vascularisation in preterm infants caused by unregulated VEGF expression in response to relative hyperoxia; screened in all <32-week or <1500 g neonates by ophthalmology; treated with laser photocoagulation or anti-VEGF injection.

Haemolytic disease of the newborn caused by Rh-negative mother sensitised to the Rh D antigen, producing IgG anti-D that crosses the placenta and haemolyses Rh-positive fetal red cells; preventable with anti-D prophylaxis (Rhogam).

An elevated, white ridge with height and width at the vascular-avascular junction in ROP; precedes the extraretinal proliferation of Stage 3; may have 'popcorn' vessels (isolated tufts of new vessels just posterior to the ridge) at Stage 2.

The most posterior retinal zone in ROP classification, defined as a circle centred on the optic disc with radius equal to twice the distance from optic disc to fovea; Zone I disease is the highest-risk category, as laser is technically difficult and vessels are close to the macula.

The peripheral temporal crescent of retina beyond Zone II, reaching the temporal ora serrata; disease in Zone III alone carries the lowest risk of progression to retinal detachment and is usually managed with observation.

Clinical classification of HIE severity into three stages based on consciousness, tone, reflexes, seizures, autonomic signs, and EEG; Sarnat I = mild (hyperalert, no seizures), II = moderate (lethargic, hypotonic, seizures), III = severe (coma, flaccid).

A hollow, boat-shaped abdominal contour in a newborn caused by herniation of abdominal contents into the thorax through a diaphragmatic defect (congenital diaphragmatic hernia); the opposite of the normally rounded neonatal abdomen.

Hardening of skin and subcutaneous tissue in severe hypothermia or serious illness in neonates; reflects crystallisation of subcutaneous fat and is a pre-terminal sign indicating critical metabolic failure.

A deeper state of apnoea following failed primary apnoea, characterised by falling heart rate and unresponsiveness to stimulation; requires positive pressure ventilation to reverse.

The delayed phase of HIE (hours 6–72), driven by excitotoxicity, oxidative stress, nitric oxide toxicity, and apoptosis; represents the primary target of therapeutic hypothermia.

A bag-mask ventilation device that refills automatically without requiring a gas flow; the standard PPV device in neonatal resuscitation; the 250 mL size is used for term neonates.

A panel of five laboratory criteria used to support the diagnosis of neonatal sepsis: TLC, I:T ratio, CRP, micro-ESR, and gastric aspirate polymorphs; a screen is positive if ≥3 of 5 criteria are met; sensitivity ~90%, specificity ~70%.

An incubator or radiant warmer that automatically adjusts heater output to maintain a target skin or air temperature; safer than manual mode for neonates because it prevents both hypothermia and hyperthermia from occurring with standard settings.

Axillary temperature <32°C in a neonate; an emergency requiring NICU admission, radiant warmer, IV access, glucose, treatment of metabolic complications (acidosis, coagulopathy, pulmonary haemorrhage), and full sepsis evaluation.

Birth weight below the 10th percentile for the corresponding gestational age, plotted on a standardised growth chart (Fenton or WHO); does NOT define the cause (may be constitutional or pathological IUGR).

Obstetric emergency in which the fetal anterior shoulder fails to deliver with routine traction after the head has been delivered, requiring specific manoeuvres (McRoberts, suprapubic pressure, rotational manoeuvres).

Syndrome of inappropriate antidiuretic hormone secretion; occurs in HIE due to hypothalamic injury, causing fluid retention, hyponatraemia, and worsened cerebral oedema; managed by fluid restriction to 60–80 mL/kg/day.

A phosphodiesterase type-5 inhibitor that promotes pulmonary vasodilation by increasing cGMP in smooth muscle cells; used at 0.5–2 mg/kg TDS for PAH complicating BPD in neonates and infants; reduces right ventricular afterload.

A five-parameter scoring system (upper/lower chest retraction, xiphoid retraction, nares dilatation, expiratory grunt) used in neonatal intensive care to grade the severity of respiratory distress.

Positioning of the neonate in direct contact with the parent's chest skin; provides regulated thermal environment matching the thermoneutral zone, promotes breastfeeding, reduces apnoea and hypothermia, and has neurodevelopmental benefits; the primary thermal and developmental intervention for stable LBW neonates (KMC).

Birth weight below the 10th centile for gestational age on a standard growth chart; implies intrauterine growth restriction and carries risks of hypoglycaemia, polycythaemia, and hypothermia.

Life-threatening haemorrhage into the loose areolar tissue beneath the galea aponeurotica; crosses sutures widely, can accommodate the entire neonatal blood volume (~260 mL), typically follows vacuum delivery.

Located between the periosteum and the outer surface of the underlying bone; the anatomical location of a cephalhaematoma.

The most common type of neonatal seizure; characterised by eye deviation, lip smacking, sucking, cycling limb movements, or apnoea; non-suppressible by limb restraint; may lack EEG correlate but represent significant brain dysfunction.

The gold standard diagnostic procedure for Hirschsprung disease; a mucosal biopsy taken at the bedside from the posterior rectal wall 1–2 cm above the dentate line is examined for the absence of ganglion cells and increased acetylcholinesterase staining.

A multicentre RCT (2010) enrolling preterm infants at 24–27+6 weeks; compared SpO2 targets 85–89% vs 91–95%; found lower target reduced ROP but significantly increased mortality — establishing 90–95% as the evidence-based compromise range.

A mixture of phospholipids (predominantly DPPC) and proteins secreted by type II alveolar pneumocytes that reduces surface tension in alveoli, preventing collapse at end-expiration; mature by approximately 34 weeks gestation.

Exogenous surfactant (beractant, poractant alfa) administered intratracheally or via LISA (less invasive surfactant administration) to treat respiratory distress syndrome in preterm neonates; reduces surface tension, prevents alveolar collapse, reduces oxygen requirements and RDS severity, thereby reducing BPD risk.

IUGR pattern in which all body compartments are proportionally reduced (head, length, and weight equally affected); caused by early-onset insults (chromosomal abnormalities, TORCH infections, severe malnutrition); carries a worse neurodevelopmental prognosis.

A baby born between 37+0 and 41+6 weeks of completed gestation, with expected weight 2,500–4,000 g and the full complement of physiological adaptations to extrauterine life.

Whole-body cooling to 33–34°C for 72 hours, started within 6 hours of birth, for term neonates (≥36 weeks) with moderate-to-severe HIE; reduces neuronal apoptosis by slowing secondary energy failure; reduces mortality and neurodevelopmental disability.

Reduction of core body temperature to 33–34°C for 72 hours in neonates ≥36 weeks with moderate-severe HIE (Sarnat II/III) when initiated within 6 hours of birth; reduces death or major neurodisability by 25–30%.

The range of environmental temperature in which a neonate maintains normal body temperature with minimal metabolic energy expenditure (minimal oxygen consumption); approximately 32–34°C for a term neonate and 35–37°C for a very preterm neonate.

The physiological process by which the body maintains core temperature within a narrow range through mechanisms of heat production (thermogenesis), heat conservation (vasoconstriction, posture), and heat loss (sweating, vasodilation); governed by the hypothalamus.

A group of congenital/perinatal infections: Toxoplasma, Other (syphilis, HBV, VZV), Rubella, CMV, HSV; transmitted transplacentally or at delivery; cause multisystem neonatal disease with hearing loss, chorioretinitis, calcifications, hepatosplenomegaly, and cardiac defects.

An abnormal connection between the trachea and oesophagus resulting from failure of separation of the tracheo-oesophageal septum; usually associated with oesophageal atresia (Gross Type C — OA + distal TOF — is the most common type, ~85%).

A non-invasive optical measurement of bilirubin in skin and subcutaneous tissue; validated as a screening tool for TSB ≤15 mg/dL in term/near-term infants but must be confirmed by serum TSB when elevated or before initiating phototherapy.

The most common cause of respiratory distress in term neonates; caused by delayed clearance of fetal lung fluid, especially after elective caesarean section; characterised by perihilar streaky opacities on CXR; self-limiting within 24–72 hours.

The preferred neonatal chest compression method: both thumbs compress the lower sternum while the hands encircle and support the thorax; generates superior coronary perfusion pressure compared to two-finger technique.

The treatment threshold for ROP, comprising: Zone I (any stage with plus disease, or Stage 3 without plus) OR Zone II (Stage 2–3 with plus disease); requires laser photocoagulation or intravitreal anti-VEGF within 48–72 hours of diagnosis.

Subclinical ROP requiring close monitoring but not immediate treatment: Zone I Stage 1–2 without plus disease, or Zone II Stage 3 without plus; treat if it progresses to Type 1.

Uncoupling protein 1; located in the inner mitochondrial membrane of brown adipocytes; allows protons to bypass ATP synthase, dissipating the electrochemical gradient as heat rather than ATP; the molecular basis of non-shivering thermogenesis.

A catheter inserted into the umbilical vein, the preferred emergency vascular access route in neonatal resuscitation for medications and volume; can be established within 1–2 minutes by a trained provider.

The practice of giving Vitamin K1 1 mg IM to every newborn at birth regardless of risk factors, as recommended by IAP and included in the National Immunization Schedule; effectively prevents classic and most late VKDB.

A non-random co-occurrence of Vertebral defects, Anal atresia, Cardiac defects, Tracheo-Esophageal fistula, Renal anomalies, and Limb defects; found in up to 50% of oesophageal atresia and anorectal malformation cases; mandates a systematic search for all components.

An oral prodrug of ganciclovir used for treating symptomatic congenital CMV infection; dose 16 mg/kg/dose orally twice daily for 6 months; reduces the rate of CMV-associated hearing deterioration; requires monitoring for neutropenia.

A signalling protein that drives angiogenesis and vascular permeability; upregulated by hypoxia via HIF-1α; suppressed by hyperoxia — this suppression causes retinal vessel regression in Phase 1 ROP; pathological VEGF surge in Phase 2 drives extraretinal neovascularisation.

Haemorrhagic disease of the newborn caused by low vitamin K levels at birth (poor placental transfer + absent gut flora); prevented by routine vitamin K₁ 1 mg IM at birth.

Intramuscular injection of 1 mg vitamin K (0.5 mg if birth weight <1.5 kg) given to all neonates at birth to prevent haemorrhagic disease of the newborn; critically important in birth injuries with associated haemorrhage.

The natural plant-derived form of Vitamin K found in green leafy vegetables and used for prophylaxis and treatment of VKDB; given as 1 mg IM at birth for all neonates.

Vitamin K Deficiency Bleeding — the modern term for haemorrhagic disease of the newborn; bleeding caused by deficiency of Vitamin K-dependent clotting factors (II, VII, IX, X) in neonates and young infants.

The characteristic arm posture in Erb palsy: shoulder adducted and internally rotated, elbow extended, forearm pronated, wrist flexed — resulting from loss of C5-C6 innervated muscles.

WHO 10-link strategy for preventing neonatal hypothermia: warm delivery room, immediate drying, skin-to-skin contact, breastfeeding, postponed bathing, appropriate clothing, mother-newborn togetherness, warm transport, warm resuscitation, and training of birth attendants.