Household air pollution exposures over pregnancy and maternal blood pressure trajectories through 8 years postpartum: Evidence from the Ghana Randomized Air Pollution and Health Study (GRAPHS)

BACKGROUND: Household air pollution is a major contributor to cardiovascular disease burden in women in Sub-Saharan Africa. However, little is known about exposures during pregnancy or the effect of clean cooking interventions on postpartum blood pressure trajectories. METHODS: The Ghana Randomized Air Pollution and Health Study (GRAPHS) randomized 1414 non-smoking women in the first and second trimesters to liquefied petroleum gas (LPG) or improved biomass stoves - vs control (traditional three-stone open fire). Personal exposure to carbon monoxide (CO) was measured at four prenatal timepoints and three times over the first postpartum year. A subset of 690 participants were prospectively followed with annual resting BP measurements at 2, 4, 5, 6, 7, and 8 years postpartum. We employed linear mixed effects models to determine effect of GRAPHS interventions on postpartum BP, and to examine associations between prenatal and postnatal CO and postpartum BP. RESULTS: The LPG intervention was associated with 3.54 mmHg (95 % CI -5.55, -1.53) lower change in systolic BP from enrolment through 8 years postpartum, and 2.27 mmHg (95 % CI -3.61, -0.93) lower change in diastolic BP from enrolment through 8 years postpartum, as compared to control. In exposure-response analysis, average prenatal CO was positively associated with change in systolic BP from enrolment (β = 0.71 mmHg, 95 % CI 0.08, 1.30, per doubling of CO) in pregnant persons carrying male fetuses. CONCLUSIONS: The LPG cookstove intervention initiated in early pregnancy and maintained through the first postpartum year was associated with lower systolic and diastolic BP trajectories through 8 years postpartum. These findings support the need to integrate clean cooking solutions into existing antenatal care packages.