Incidence and risk factors of low birth weight in a rural district of Bangladesh: a prospective cohort study

Background Low birth weight (LBW, birthweight < 2500 gm) is associated with a significantly increased risk of morbidity and mortality during infancy and is an important contributor to childhood developmental delays. Methods To estimate the incidence of LBW and identify its risk factors, we analyzed data from a population-based cohort study, the Aetiology of Neonatal Infections in South Asia, conducted in two sub-districts of Sylhet district of Bangladesh. The study followed 24,271 pregnant women from 2011 to 2013. The final analysis included 17,643 singleton liveborn babies with birthweight data available. To identify associated factors of LBW, we calculated adjusted risk ratios (ARRs) and 95% confidence intervals (CIs) using multivariable modified Poisson regression with robust variance. Results The incidence of LBW was 27.61% (95% CI: 26.96%-28.28%). Significant risk factors of LBW were no education of father [ARR 1.09 (95% CI: 1.01–1.17)]; non-Muslim religion [ARR 1.32 (95% CI: 1.20–1.45)]; lowest household quintile [ARR 1.31 (95% CI: 1.19–1.44)], second lowest household quintile [ARR 1.26 (95% CI: 1.15–1.38)], and middle household quintile [ARR 1.16 (95% CI: 1.06–1.26)], compared to the highest quintile; primiparity [ARR 1.59 (1.49–1.69)]; maternal mid-arm circumference (MUAC) < 22 cm [ARR 1.19 (95% CI: 1.13–1.25)]; tobacco consumption during pregnancy [ARR 1.15 (95% CI: 1.08–1.23)]; pregnancy complications [ARR 1.10 (95% CI: 1.03–1.17)]; no antenatal visits with qualified providers [ARR 1.16 (95% CI: 1.07–1.25)]; no antenatal iron consumption [ARR 1.12 (95% CI: 1.04–1.21)]; <2 doses of antenatal TT immunization by mothers [ARR 1.19 (95% CI: 1.09–1.31)] and no TT doses [ARR 1.16 (95% CI: 1.09–1.23)] ; residence ≥ 15 km from sub-district hospitals [ARR 1.12 (95%CI 1.07–1.18)]; gestational age at birth: <32 weeks [ARR 1.88 (95% CI: 1.71–2.06)], 32–33 weeks [ARR 1.61 (95% CI: 1.46–1.77)], and 34–36 weeks[ARR 1.42 (95% CI: 1.34–1.51); and female baby [ARR 1.19 (95% CI: 1.14–1.25)]. Conclusions The burden of LBW was high in rural Bangladesh. Multiple antenatal factors, including maternal undernutrition, tobacco use, and suboptimal antenatal care were associated with increased risk of LBW. Maternal and child health programs should prioritize interventions to address these factors. Clinical trial number: Not applicable