OG12.11,OG16.4 | Intrauterine Growth Retardation — Summary & Reflection

KEY TAKEAWAYS

IUGR — Key Summary Points:

• Definition and distinction: IUGR = failure to reach growth potential (EFW <10th centile on customised chart with abnormal growth velocity); SGA = birth weight <10th centile — not synonymous. Customised GROW charts preferred over population charts.

• Types: Symmetrical IUGR (early onset, proportionate, brain NOT spared, cause often chromosomal/TORCH); asymmetrical IUGR (late onset, brain-sparing, AC disproportionately small, cause = uteroplacental insufficiency — the majority).

• Causes: maternal (HDP most common, thrombophilia, APS, anaemia, malnutrition, smoking), placental (failed trophoblastic invasion, infarcts, velamentous cord), fetal (chromosomal, structural, TORCH infections).

• Diagnosis: serial SFH on customised chart → ultrasound biometry (HC, AC, FL, EFW, AFI) → Doppler (UA, MCA, CPR, DV).

• Doppler escalation ladder: normal UA → elevated S/D → AEDF → REDF → abnormal MCA/CPR → DV a-wave absent/reversed → BPP deteriorates → CTG late changes. Each step indicates worsening compromise.

• Management: balance prematurity vs in-utero hypoxia. Corticosteroids <34 weeks; MgSO4 neuroprotection <32 weeks. Deliver: late-onset mild IUGR by 37–38 weeks; early IUGR with AEDF — trigger on DV abnormality or BPP ≤4 (TRUFFLE); REDF deliver by 34 weeks; DV absent/reversed a-wave — deliver regardless of gestation if viable.

• Prevention: low-dose aspirin before 16 weeks (strongest evidence), treat modifiable risk factors, optimise nutrition, smoking cessation.

• Barker hypothesis: IUGR programmes fetal metabolism via epigenetic mechanisms → adult cardiometabolic disease (hypertension, T2DM, CHD).

REFLECT

Think about the last time you observed an ultrasound scan in the antenatal clinic or reviewed a biometry report. How comfortable are you with interpreting the HC/AC ratio and recognising the pattern of asymmetric IUGR? If a patient asked you 'Doctor, why is my baby small and what does that mean for my baby's future?', what would you tell her about Doppler surveillance, the timing of delivery, and the long-term implications for her child? Reflect on how you might explain a complex clinical decision — staying pregnant longer vs delivering early — to a frightened parent in a way that is honest, compassionate, and clinically grounded. What do you feel you need to see or do in the clinical setting before you would feel confident managing an IUGR pregnancy independently under supervision?