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CM9.2-3 | CM9.2-3 | Demographic Indices and Sex Ratio — SDL Guide (Part 3)

Monitoring Sex Ratio and Evaluating Index Trends

Evaluating the success of interventions targeting the skewed sex ratio requires careful selection of monitoring indicators and a clear understanding of the timelines involved. The child sex ratio (Census-based) is measured only every ten years, making decennial data an inadequate monitoring tool for programmes that need mid-course corrections. Programme planners therefore rely on two proxy indicators between censuses: the sex ratio at birth (SRB) and the proportional sex ratio in birth registrations reported through the Civil Registration System and HMIS.

The sex ratio at birth is the number of live girl births per 1,000 live boy births. Biologically, the expected SRB is approximately 950 females per 1,000 males. An SRB below this value indicates active sex selection at birth. Monitoring SRB trends through birth registration data allows near-real-time detection of worsening or improving sex selection patterns. Some states now require SRB data to be reported monthly through HMIS.

The social and health implications of a declining sex ratio extend well beyond the direct health consequences for missing girls. International evidence from China, India, and South Korea identifies the following downstream consequences:

• Marriage squeeze — excess of men relative to women in the marriage market, beginning approximately 20-25 years after a period of low child sex ratio. This forces men to seek brides from lower-income, more distant communities, or remain unmarried — both associated with adverse health outcomes (higher male mortality, mental health morbidity).
• Trafficking — communities with severe marriage squeeze import women from poorer regions, creating trafficking networks. India's National Crime Records Bureau data confirm that states with the lowest sex ratios have the highest rates of trafficking.
• Gender-based violence — evidence from China's one-child era and India's district-level data links low sex ratios to higher rates of rape, assault, and femicide, as male competition for scarce female partners increases.
• Fertility rebound — in some communities, the loss of girl children paradoxically increases fertility: families who lose daughters to sex-selective abortion continue having children until they achieve their desired number of sons, increasing total births per couple.

Evaluating the full impact of interventions therefore requires multi-decade surveillance combining child sex ratio (Census), SRB (HMIS/CRS), girl child school enrolment (education data), and violence against women indicators.

Applying Indices to Public Health Decisions

The true test of mastery over demographic indices is the ability to select the right measure for a given decision, compute it correctly from available data, and interpret it in the context of an intervention. This section works through India-specific examples that you are likely to encounter in community medicine postings and examinations.

Consider the following decision-support applications of demographic indices in a typical district health planning exercise:

First, when a district health officer wants to prioritise districts for family planning service expansion, the TFR is the appropriate index — not the CBR, because TFR is age-standardised and directly comparable across districts with different age structures. A district with TFR > 3.0 has a very different family planning need from one with TFR of 2.0, even if their CBRs are similar because the higher-TFR district has a younger population base.

Second, when comparing child health programme performance across states or districts, IMR is the standard benchmark, supplemented by U5MR for comprehensive child survival assessment. When evaluating neonatal care specifically, the Neonatal Mortality Rate (NMR) — deaths in the first 28 days per 1,000 live births — is used. India's NFHS-5 NMR is 29.5.

Third, when assessing a district's progress on gender equity, the child sex ratio from the most recent HMIS birth data provides a proxy between censuses. The Beti Bachao Beti Padhao dashboard tracks SRB monthly for all districts. A sustained upward trend in SRB (more girl births relative to boy births, approaching the biological norm of 950) is the key performance indicator.

Fourth, when making the case for geriatric services investment, the dependency ratio trend and the population pyramid shape signal the ageing burden. Kerala's constrictive pyramid — with a broad middle, narrow base, and expanding top — already forecasts a geriatric care demand that will stress its health system within one generation, even though Kerala's overall health indices are exemplary.

In each case, the index is not a number in isolation — it is evidence in an argument for resource allocation, and its power depends on your ability to defend its numerator, denominator, and comparability.