Factors Associated with Antenatal Care Service Utilization Under the Eight-Contact Visit Model in Zanzibar

Background The World Health Organization (WHO) introduced the eight-contact model of antenatal care (ANC) in 2016 to enhance maternal and perinatal outcomes. Despite widespread implementation, adherence to all eight visits remains suboptimal in many low- and middle-income settings, including Zanzibar. Objective To assess factors associated with utilization of ANC services under the eight-contact model among pregnant women in Zanzibar. Methods A cross-sectional analytical study was conducted among 852 postnatal women attending 18 health facilities across Unguja and Pemba. A structured questionnaire was administered via Open Data Kit (ODK). Data were analyzed using Stata 17. Descriptive statistics summarized participants’ characteristics, while chi-square and logistic regression identified factors independently associated with completing eight or more ANC visits. A p-value < 0.05 was considered statistically significant. Results Only 23.0% of women completed ≥ 8ANC contacts. Early ANC booking before 16 weeks was strongly associated with optimal utilization (AOR = 28.89, 95% CI: 11.02–75.76; p = 0.001). Primigravida women had higher odds of completing eight contacts compared to those with more than four pregnancies (AOR = 24.31, 95% CI: 4.09–144.50; p = 0.001). Higher household income (> 1,000,000 TZS/month) was also associated with optimal utilization (AOR = 1.79, 95% CI: 1.02–3.14; p = 0.042). Partner involvement (AOR = 2.07, 95% CI: 1.26–3.42; p = 0.004) and perception of male-friendly clinic environments (AOR = 2.44, 95% CI: 1.38–4.32; p = 0.002) significantly increased the likelihood of completing eight ANC contacts. Conclusion Completion of the eight-contact ANC model remains low in Zanzibar. Key determinants include timing of ANC initiation, parity, household income, partner support, and clinic environments. Strengthening community awareness on early booking, reducing financial barriers, and promoting male-friendly health services could improve ANC utilization and maternal health outcomes.