Interpregnancy Interval and Child Health Outcomes in India: Evidence from Three Recent Rounds of National Family Health Survey.

Introduction: Short interpregnancy interval (IPI) is a well-known risk factor for preterm births and low birth weights. However, research on the association between interpregnancy interval (IPI) and health outcomes in children under age 5 is limited in India. We examined the associations between IPI and five child health outcomes in India.

Methods: We used nationally representative cross-sectional data from three rounds of National Family Health Survey (NFHS) conducted in India during 2005-06, 2015-16 and 2019-21 to examine the associations between IPI [categorized as < 12 months, 12-17 months, 18-23 months (ref), 24-35 months, and 36-59 months] and five child health outcomes - neonatal mortality, postneonatal mortality, diarrhea and/or acute respiratory infections (ARI), stunting, and underweight, for the total sample and, secondarily, using sex-stratified analyses. We used multivariable and mother fixed-effects binary logistic regressions to examine the associations.

Results: 3% and 2% of infants died during the neonatal and postneonatal period, respectively. Thirteen, 40, and 37% of children had diarrhea and/or ARI, were stunted, and were underweight, respectively. IPI < 12 months was associated with higher odds of diarrhea and/or ARI (OR: 1.11; 95% CI: 1.05-1.18), stunting (OR: 1.13; 95% CI: 1.08-1.18) and underweight (OR: 1.06; 95% CI: 1.01-1.11). Mother fixed-effects adjustments confirmed these associations and also found that births with IPI of 12-17 months and 36-59 months had higher odds of stunting, and IPI of 12-17 months was also associated with higher odds of underweight.

Discussion: Our findings indicate that IPIs shorter than 12 months are a risk factor for diarrhea and/or ARI, and IPIs shorter than 12 months and 12-17 months are risk factors for stunting and underweight among children under 5 in India. Mother fixed-effects models allowed us to adjust our estimates for unobserved heterogeneity; this has rarely been done before. Increases in birth spacing may improve child health outcomes in India.