Objectives: To investigate the relationship between adolescent pregnancy and neonatal mortality in a nutritionally deprived population in rural Nepal, and to determine mechanisms through which low maternal age may affect neonatal mortality.
Design: Nested cohort study using data from a population-based, cluster-randomized, placebo-controlled trial of newborn skin and umbilical cord cleansing with chlorhexidine.
Setting: Sarlahi District of Nepal.
Participants: Live-born singleton infants of mothers younger than 25 years who were either parity 0 or 1 (n = 10,745).
Main exposure: Maternal age at birth of offspring.
Outcome measure: Crude and adjusted odds ratios of neonatal mortality by maternal age category.
Results: Infants born to mothers aged 12 to 15 years were at a higher risk of neonatal mortality than those born to women aged 20 to 24 years (odds ratio, 2.24; 95% confidence interval, 1.40-3.59). After adjustment for confounders, there was a 53% excess risk of neonatal mortality among infants born to mothers in the youngest vs oldest age category (1.53; 0.90-2.60). This association was attenuated on further adjustment for low birth weight, preterm birth, or small-for-gestational-age births.
Conclusions: The higher risk of neonatal mortality among younger mothers in this setting is partially explained by differences in socioeconomic factors in younger vs older mothers; risk is mediated primarily through preterm delivery, low birth weight, newborns being small for gestational age, and/or some interaction of these variables.
Trial registration: clinicaltrials.gov Identifier: NCT00109616.