Extreme weather events and malaria prevention in pregnancy: a mediation analysis of antenatal care and sulfadoxine-pyrimethamine use in two malaria-endemic counties of Kenya.

BACKGROUND

Climate change threatens maternal, and newborn health, particularly by exacerbating climate-sensitive diseases like malaria. Malaria in pregnancy (MiP) contributes to maternal anaemia, stillbirth, preterm delivery, and low birth weight. In Kenya's Lake Victoria basin, recurrent floods and droughts disrupt antenatal care (ANC), the main delivery platform for intermittent preventive treatment of MiP with sulfadoxine-pyrimethamine (IPTp-SP). The extent to which these extreme weather events affect IPTp-SP uptake through ANC attendance remains unexplored.

METHODS

Data are drawn from a cross-sectional household survey conducted under the revive IPTp-SP project among women who had given birth to a live baby in the last 24 months preceding the interview in malaria-endemic counties of Kisumu and Migori. Exposure was self-reported extreme weather events in the past 12 months; the outcome was completion of three or more IPTp-SP doses (IPTp₃ +); and the mediator was attendance of ≥ 4 ANC visits (ANC4+). Using a counterfactual mediation framework, we decomposed the total effect of climate shock on IPTp₃ + into natural direct and indirect effects via ANC4+, adjusting for covariates. Models accounted for the complex survey design, with bootstrapping to estimate 95% confidence intervals (CI) for indirect effects.

RESULTS

IPTp₃ + coverage was lower among shock-exposed pregnancies (49.5%) versus unexposed (58.8%). Extreme weather events were associated with reduction in ANC4+ attendance (- 0.23, 95% CI - 0.41 to - 0.05). ANC4+ completion strongly predicted IPTp₃ + uptake (1.71, 95% CI 1.42-2.00). The total effect of shocks on IPTp₃ + was -0.45 (95% CI - 0.68 to - 0.23), of which 76.6% was mediated through ANC. After adjustment, the total effect attenuated (-0.27, 95% CI - 0.56 to 0.02) and was no longer significant. Effects were stronger in flood-prone Kisumu than in Migori.

CONCLUSIONS

Extreme weather events reduced IPTp₃ + uptake primarily through ANC disruption in unadjusted models, with effects concentrated in Kisumu. However, these associations attenuated after adjustment, suggesting the role of underlying socioeconomic and contextual vulnerabilities.