Social inequalities in low birthweight outcomes in Sri Lanka: evidence from the Demographic and Health Survey 2016

Objective To investigate social inequalities underlying low birthweight (LBW) outcomes in Sri Lanka. Design Cross-sectional study. Setting This study used the Sri Lanka Demographic and Health Survey 2016, the first such survey to cover the entire country since the Civil War ended in 2001. Participants Birthweight data extracted from the child health development records available for 7713 babies born between January 2011 and the date of interview in 2016. Outcome measures The main outcome variable was birth weight, classified as LBW (<= 2500g) and normal. Methods We applied random intercept three-level logistic regression to examine the association between LBW and maternal, socioeconomic and geographic variables. Concentration indices were estimated for different population subgroups. Results The population-level prevalence of LBW was 16.9% but was significantly higher in the estate sector (28.4%) compared with rural (16.6%) and urban (13.6%) areas. Negative concentration indices suggest a relatively higher concentration of LBW in poor households in rural areas and the estate sector. Results from fixed effects logistic regression models confirmed our hypothesis of significantly higher risk of LBW outcomes across poorer households and Indian Tamil communities (AOR 1.70, 95%CI 1.02 to 2.83, p<0.05). Results from random intercept models confirmed there was substantial unobserved variation in LBW outcomes at the mother level. The effect of maternal biological variables was larger than that of socioeconomic factors. Conclusion LBW rates are significantly higher among babies born in poorer households and Indian Tamil communities. The findings highlight the need for nutrition interventions targeting pregnant women of Indian Tamil ethnicity and those living in economically deprived households.