Community Mental Health Service Antenatal Care Visit Count and Postnatal Depression Detection in Zimbabwean Clinics: A Regression-Discontinuity Estimation of Contact-Intensity Exposure

Postnatal depression remains under-detected in low-resource antenatal systems, and the contribution of routine antenatal contact frequency to detection is poorly specified. The design treats the visit-count schedule as an instrument-like assignment variable, with clinics on either side of the threshold differing in recommended contact intensity but not in catchment composition. Using the DHS Program indicator 'Antenatal care provider: Doctor' (RH_ANCP_W_DOC) across 38 African countries and 549 country-survey observations from 1986 to 2025 (mean 15.06, SD 16.47), the paper calibrates the plausible range of contact-intensity exposure and specifies the estimand, bandwidth, running-variable construction and falsification tests required before the design can be fielded. The contribution is a pre-specified identification strategy for a question that current Zimbabwean clinic data cannot yet answer, together with a transparent account of the assumptions that must hold for the resulting estimate to be interpreted causally.