Association between completing at least eight antenatal care contacts and maternal anaemia in Ghana: a cross-sectional study using causal machine learning

Background: Maternal anaemia remains a pressing global health challenge, with a notable burden in low- and middle-income countries. Existing studies in sub-Saharan Africa have largely relied on average associations, thereby concealing key variation among women and failing to account for heterogeneity. Objective: To assess the association between completing at least eight antenatal care (ANC) contacts and maternal anaemia in Ghana and to explore heterogeneity in this association using causal machine learning. Design: An institution-based cross-sectional study was conducted using a retrospective review of medical records and causal machine learning analysis. Setting: Juaben Government Hospital. Participants: Of 2326 women who delivered at the hospital, 2114 with complete data on the main exposure and outcome variables were included in the analysis. Main exposure: Completion of at least eight ANC contacts. ANC contact was defined as the in-person visit to the clinic with a healthcare professional for routine ANC services and follow-up. Main outcome: Maternal anaemia, defined as a haemoglobin level below 11 g/dL in the last ANC before delivery. Methods: A causal forest model was used to estimate the association between completing at least eight ANC contacts and maternal anaemia. Conditional average treatment effects were used to explore individual-level variation in these associations, providing policy-relevant insights. Results: Completing ≥8 ANC contacts was associated with a 6 percentage-point lower probability of maternal anaemia compared with having fewer visits (average treatment effect: -0.06, 95% CI −0.11 to −0.02). Predicted individual-level effects ranged from −0.21 to 0.09. Participants’ age, malaria prophylaxis, marital status, parity and educational level were the five most important contributors to the observed heterogeneity. Conclusions: This study demonstrated that completing ≥8 ANC contacts is associated with a lower probability of maternal anaemia, with heterogeneity across subgroups. We recommend differentiated, context-specific ANC interventions that focus on high-impact subgroups while strengthening the effectiveness and quality of care delivered at each visit.