Catchment-Level Inequities in Malaria Prevention during Pregnancy:  Public–Private Differences in IPTp3 Delivery in Oyo State, Nigeria.

Intermittent preventive treatment in pregnancy (IPTp) remains a cornerstone of malaria control in sub-Saharan Africa, yet coverage gaps persist despite widespread antenatal care (ANC) attendance. In Nigeria’s mixed health system, institutional differences between public and private facilities may contribute to uneven delivery of IPTp, but such disparities are poorly understood at operational spatial scales. This study employed a catchment-based spatial framework to evaluate IPTp3 delivery among pregnant women in Oyo State, Nigeria, using routine health facility data from DHIS2 for 2025. IPTp3 coverage was standardized against pregnancy stock derived from high-resolution WorldPop population estimates. Catchment-level indicators were compared between public and private facilities, and ownership effects were assessed using demand-adjusted regression models controlling for pregnancy burden, women-of-reproductive-age density, and catchment area. IPTp3 delivery exhibited extreme heterogeneity across catchments. Private facilities recorded substantially lower median IPTp3 coverage and a markedly higher prevalence of zero delivery despite non-zero pregnancy burden. After adjusting for demographic demand and spatial scale, private facility ownership was independently associated with significantly lower IPTp3 delivery (p < 0.001). Aggregated ward- and LGA-level summaries obscured these micro-scale inequities, highlighting the added value of catchment-level analysis. Malaria prevention during pregnancy in Oyo State is strongly shaped by institutional factors rather than demographic demand alone. Persistent under-delivery of IPTp3 in private facility catchments represents a critical equity gap that may undermine progress toward malaria elimination and maternal health goals. Strengthening private-sector integration into malaria prevention programs and adopting catchment-based monitoring frameworks are essential for achieving more equitable IPTp coverage.