The neonatal mortality risk of vulnerable newborns in rural Bangladesh: A prospective cohort study within the Shonjibon trial.

OBJECTIVES

Preterm birth (<37 weeks), low birth weight (2500 g), small-for-gestational-age (birth weight <10th percentile of a given reference), and large-for-gestational-age (birth weight >90th percentile of a given reference) are indicators of vulnerable infants and risk factors for neonatal mortality. We estimated the prevalence and risk of neonatal mortality associated with these phenotypes and their mutually exclusive phenotypes in rural Bangladesh.

METHODS

We conducted a prospective cohort study in five rural districts of Bangladesh using data collected from births in the Shonjibon Trial from 2013 to 2015. We estimated the prevalence of preterm birth, low birth weight, small-for-gestational-age, and large-for-gestational-age infants, individually and for mutually exclusive phenotypes, using a combination of these phenotypes. Neonatal mortality associated with preterm birth, low birth weight, small-for-gestational-age, large-for-gestational-age, and mutually exclusive phenotypes were calculated using Kaplan-Meier survival analysis and Poisson regression for adjusted relative risks (aRR) with 95% confidence intervals (CI).

RESULTS

We included 24,314 live births in this study. The prevalence of preterm birth, low birth weight, small-for-gestational-age, and large-for-gestational-age was 26.2%, 22.9%, 41.7%, and 8.2%, respectively. The prevalence of babies born appropriate for gestational age, with term gestation (≥37 weeks) and normal birth weight (≥2500 g) was 33.3%. For individual phenotypes, the neonatal mortality risk was approximately 3-fold for preterm, low birth weight, and large-for-gestational-age newborns and 1.5-fold for small-for-gestational-age newborns compared with appropriate-for-gestational-age, term, and normal birth weight newborns. The risk of neonatal mortality for mutually exclusive phenotypes was highest in small-for-gestational-age, preterm, and low birth weight newborns (aRR = 6.3, 95% CI 4.1-9.6) relative to appropriate for gestational age, term, and normal birth weight newborns.

CONCLUSIONS

In rural Bangladesh, most infants are born with one or more vulnerable phenotypes associated with an increased risk of neonatal mortality. Our findings highlight the value of categorising newborns using mutually exclusive vulnerable phenotypes and their neonatal mortality risks, which can be used to tailor interventions to improve survival.