The association of maternal age with adverse neonatal outcomes in Lusaka, Zambia: a prospective cohort study

Background: Pregnancy among adolescents, whether intended or not, is a public health concern as it is generally considered high risk for both mothers and their newborns. In Zambia, where many women engage in early sexual behaviour or marry at a young age, 28.5% of girls aged 15-19 years were pregnant with their first child in the year 2013-2014. This study sought to explore associations between maternal age and neonatal outcomes among pregnant women in Lusaka, Zambia.

Methods: This was a secondary analysis of data nested within a larger population-based prospective cohort study which was implemented in three government health facilities-two first level hospitals and one clinic in Lusaka, Zambia. Women presenting to the study sites for antenatal care were enrolled into the study and followed up for collection of maternal and neonatal outcomes at 7, 28 and 42 days postpartum. The study's primary outcomes were the incidence of maternal and newborn complications and factors associated with adverse neonatal outcomes. Statistical significance was evaluated at a significance level of P < 0.05.

Results: The study included 11,501 women, 15.6% of whom were adolescents aged 10-19 years. Generally, adolescence did not have statistically significant associations with poor maternal health outcomes. However, the risk of experiencing obstructed labour, premature rupture of membranes and postpartum hemorrhage was higher among adolescents than women aged 20-24 years while the risk of severe infection was lower and non-significant. Adolescents also had 1.36 times the odds of having a low birthweight baby (95% CI 1.12, 1.66) and were at risk of preterm birth (aOR = 1.40, 95% CI 1.06, 1.84). Their newborns were in need of bag and mask resuscitation at birth (aOR = 0.62, 95% CI 0.41, 0.93). Advanced maternal age was significantly associated with increased odds of hypertension/ pre-eclampsia (95% CI 1.54, 5.89) and preterm labour (aOR = 2.78, 95% CI 1.24, 6.21).

Conclusions: Adolescence is a risk factor for selected pregnancy outcomes in urban health facilities in Lusaka, Zambia. Health care workers should intensify the provision of targeted services to improve neonatal health outcomes.

Trial registration: Clinical trial number and URL: NCT03923023 (Retrospectively registered). Clinical trial registration date: April 22, 2019.