Edmond Junisa Sellu^{1, 2}, Samuel Joseph Bebeley¹, Prince Tongor Mabey^1,, Joseph James Mbavai³

This study examined the dose-response relationship between multidimensional male partner involvement and both maternal healthcare utilisation and newborn outcomes and compared the involvement gradient with the household wealth gradient in Sierra Leone. A dyadic cross-sectional survey was conducted among 500 mother-partner couples recruited by stratified cluster sampling across 15 districts between January and June 2026. Involvement was measured using a 30-item Male Involvement Index (MII, 0-100) administered separately to both partners by sex-matched enumerators. Internal consistency of the 30-item women's instrument was good (Cronbach's alpha 0.855; men's instrument 0.782). The composite was analysed continuously and in tertiles; tertiles were used because they yield approximately equal-sized groups from the observed distribution and permit inspection of monotonicity without imposing a linear functional form. Primary outcomes were four or more antenatal contacts (ANC4+), facility-based delivery and skilled birth attendance; secondary newborn outcomes were early breastfeeding initiation within one hour, postnatal care within 48 hours and child survival to the time of survey. Analysis used chi-square tests with Cramér's V for the graded contrasts, independent samples t-tests and Pearson correlation for the newborn objective, and multivariable binary logistic regression with sequential adjustment for the independent estimates. A monotonically ascending crude gradient was observed for all three primary outcomes: ANC4+ rose from 60.8% to 77.4% (+16.6 percentage points; χ² = 11.010, p = 0.004), facility delivery from 63.6% to 76.2% (+12.6; χ² = 6.376, p = 0.041) and skilled birth attendance from 68.8% to 81.1% (+12.3; χ² = 6.903, p = 0.032). The crude gradients for facility delivery and skilled birth attendance did not survive adjustment; the ANC4+ gradient was attenuated by 44% and no longer reached significance (AOR 1.56, 95% CI 0.92 - 2.65). The unadjusted odds ratio for the highest vs. lowest involvement tertile was 1.83 (95% CI: 1.14 - 2.94) for facility delivery, but 0.88 (95% CI: 0.50 - 1.57) after full adjustment. Adding household wealth alone removed 97.6% of the crude facility-delivery association on the log-odds scale. Per-unit adjusted odds ratios were near null (facility delivery AOR = 0.999, 95% CI: 0.983 - 1.015). The categorization into tertiles did not create the crude association, as the continuous specification reproduced it (crude per-unit OR = 1.019, 95% CI: 1.006 - 1.033). Wealth quintile remained strongly associated with facility delivery after adjustment (AOR = 2.228, 95% CI: 1.853 - 2.679; p < 0.001). The facility-delivery prevalence gap between the poorest and wealthiest quintiles was 57.0 percentage points, which is 4.5 times the 12.6-point difference between the lowest and highest involvement tertiles for the same outcome (57.0 ÷ 12.6 = 4.52); the corresponding gap in skilled birth attendance was 53.0 points. Newborn outcomes did not differ significantly between tertiles (all p ≥ 0.40). All the domain-outcome correlations were negligible (range −0.065 to +0.046; all p ≥ 0.14). The study was powered to detect differences of 4.9 to 14.4 percentage points, but the observed differences were 1.9 to 4.2 points, with only 5.1 points of attainable headroom for the survival endpoint. No wealth-by-involvement interaction was detected for any outcome. Household poverty showed stronger associations with maternal healthcare utilisation than male partner involvement. Male engagement should complement, not replace, demand-side financial protection. Because the design is cross-sectional, these associations should not be read causally.

Male Partner Involvement, Antenatal Care, Facility Delivery, Skilled Birth Attendance, Newborn Health, Health Equity, Sierra Leone