Alarming disparities of adolescent motherhood in Nigeria: results from 36 states and the Federal Capital Territory

Importance Nigeria has a population of 233 million people and high rates of adolescent motherhood. Reduction of adolescent motherhood is a priority and primarily aligns with the sexual and reproductive health target (indicator 3.7.2) in the specific United Nations Sustainable Development Goals (SDGs). Objective This study examined the trends and social disparities of health impacting adolescent motherhood at the state level. Design, settings and participants The study analysed 24 668 adolescent females aged 15–19 years, drawn from 36 states and the Federal Capital Territory (FCT) using four Nigerian Demographic and Health Surveys (2003–2018). This study estimated the population-weighted prevalence of adolescent motherhood and employed the average annual rate of change (AARC) to compute the state-level trends in the prevalence. The normalised concentration index was also used to understand the sociodemographic inequalities. Results The national prevalence of adolescent motherhood is 18.73%, with substantial variation in AARC and a normalised concentration index across states in different geopolitical zones. The highest prevalence of adolescent motherhood was observed in Bauchi State in the North-East at 40.65%, while the lowest was in Lagos in the South-West at 1.1%. The AARC in Bauchi was +1.7%, while in Lagos it was reported at −9.96%. Out of the 36 states and FCT, 15 (40.5%) either experienced an increasing prevalence of adolescent motherhood (29.7%) or a slow decline (10.8%) while 22 (59.5%) showed progress. With respect to the distribution of adolescent motherhood, most of the high-burden states had a negative normalised concentration index for wealth (92%), education (92%) and area of residence (72%). Moreover, highly statistically significant variations were observed between high-burden states in the North and low-burden states in the South for wealth, education, rurality, child marriage, age at first child and polygyny. Conclusions Adolescent motherhood remains persistently high in Nigeria, particularly in the northern part of the country, due to early marriage, intergenerational poverty and a lack of education. This necessitates scaling up state-specific health education programmes targeting adolescent girls in schools and government policy, enforcing the legal age of marriage to achieve the SDG 3.7.2 target.