Maternal age at birth and neonatal mortality: Associations from 67 low-income and middle-income countries

Both young and advanced maternal age have been associated with higher risks of neonatal mortality, but most studies are from high-income countries and the evidence from low- and middle-income countries (LMICs) is scarce.

To investigate the association between maternal age at delivery and neonatal mortality in LMICs.

This is a cross-sectional study using data from 159 Demographic and Health Surveys in 67 LMICs between 2000 and 2018. Maternal age at the time of the birth was the exposure variable, and neonatal mortality was the outcome. Multivariable logistic regression model taking into consideration complex survey design was performed with adjustments for maternal education level, paternal education level, rural/urban residence, country, and survey year. Subgroup analyses were performed by time of death, sex, the country's World Bank income classification, the World Health Organization region, and survey year.

A total of 1 395 746 mother-neonate pairs were included. Overall, compared with neonates born to mothers aged 25-29 years, those born to younger mothers aged 20-24, 16-19 and 12-15 years were at an increased risk of mortality (adjusted odds ratio [OR] 1.24, 95% confidence interval [CI] 1.17, 1.30; OR 1.81, 95% CI 1.71, 1.93; OR 2.29, 95% CI 1.96, 2.67, respectively). Neonates born to mothers aged 30-34, 35-39, 40-44, and ≥45 years were also at an increased risk of mortality (OR 1.09, 95% CI 1.03, 1.15; OR 1.30, 95% CI 1.21, 1.39; OR 1.50, 95% CI 1.38, 1.64; OR 1.84, 95% CI 1.54, 2.20, respectively). The results were consistent across most subgroup analyses.

Neonates born to younger (<25 years) and older mothers (≥30 years) are at increased risk of neonatal death in LMICs.