Performances of bayesian structured additive regression and logistic models in assessing factors associated with modern contraceptive use among ever-in-union women in Nigeria

Modern contraceptive prevalence was 11.5% among 31,152 ever-in-union women. Strong north-south disparities were identified, with higher uptake in urban and southern regions. A nonlinear relationship was observed between age at first marriage and contraceptive use, with 20.9% of women marrying before age 15years. Women with more than three children alive had 48% higher odds of contraceptive use (aOR = 1.48; 95% CrI: 1.24-1.66). Working women (aOR = 1.91; 95% CrI: 1.89-2.23) and those knowledgeable about modern methods (aOR = 1.78; 95% CrI: 1.66-2.25) also had higher odds.