Survival analysis and determinants of timing of first birth after marriage in Nigeria

Adeniyi Francis Fagbamigbe, University of Ibadan and North-West University, South Africa
Erhabor Idemudia, North-West University, Mafikeng Campus

The timing of first birth after marriage among women in developing countries has important consequences on the demographic dynamics of the population as it is an integral part of fertility outcomes. The study was aimed at understanding dynamics of First Birth Interval (FBI) in Nigeria and its determinants. We right-censored FBI of women aged 15-49 years using 2013 Nigeria DHS data. We used Kaplan Meier survival function and Cox Proportional Hazard (CPH) and Generalized Gamma (GG) regression to model factors affecting FBI. The median FBI in Nigeria was 1.75 years and decreased with increasing age at marriage. Women with higher education have shorter FBI than those with no education (TR=0.86(95% CI: 0.85-0.88)). Urban women were more likely to have earlier FBI (HR=1.28 95% CI: 1.24-1.32)). The fertility of women who delayed marriage remained low irrespective of their first birth interval. Delaying first birth as fertility reduction strategy should be embraced. Keywords: first birth interval, Cox proportional hazard,