Background <p>Timely initiation of antenatal care (ANC) is a critical determinant of maternal and newborn health and reflects the responsiveness of the health system to women’s needs. Adopting a systems and complexity thinking perspective, this study explored how interacting sociodemographic, reproductive, and service-related factors influence the timing of ANC initiation among postpartum women in the Nkongsamba Health District of Cameroon.</p> Methods <p>A facility-based cross-sectional study targeting women who had just given birth in 4 selected health facilities of the Nkongsamba Health District was conducted from September 2020 to December 2021. All eligible women received at the study sites during data collection were included and data collected by interview (semi-structured questionnaire) and verification of antenatal cards. Guided by a systems framework, variables were conceptualized across individual, household, and service levels. Antenatal care was said to be timely if the first visit was done within the first 12 weeks of gestation. Factors associated with timely antenatal care initiation (Yes/No), were assessed using simple and multiple logistic regression. The threshold for statistical significance was set at a p-value of 0.05. Interpretation of findings necessitated a systems-thinking lens to explain how interacting individual, social, and reproductive factors jointly shaped the timing of ANC initiation.</p> Results <p>A total of 1074 eligible participants were enrolled and the proportion of women who initiated antenatal care on time was 30.35% [95% CI: 27.68%-33.17%]. The mean gestational age at booking antenatal visit was 17.10 ± 8.08 weeks. Women who were aged above 30 years (AOR = 1.73 [95%CI: 1.15–2.59], p-value = 0.008), who had their pregnancies intended (AOR = 1.53 [95%CI: 1.01–2.33], p-value = 0.045) and those with a history of hypertension in pregnancy had their odds of initiating antenatal care on time increased compared to their counterparts. On the other hand, Women who had a history of modern contraceptive use (AOR = 0.67 [95%CI: 0.45–0.99], p-value = 0.043) and those who were not legally married (AOR = 0.60 [95%CI: 0.41–0.88], p-value = 0.008) had their odds of initiating antenatal care on time reduced compared to their counterparts.</p> Conclusion <p>Timely ANC initiation in the Nkongsamba Health District emerges from multi-level interactions between individual behaviours, social contexts, and health system factors. Interventions to improve early ANC uptake should therefore target systemic leverage points—enhancing women’s empowerment, strengthening service integration between family planning and maternity care, and improving the adaptive capacity of the maternal health system.</p>