Effects of a liquefied petroleum gas stove intervention on gestational blood pressure: intention-to-treat and exposure-response findings from the Household Air Pollution Intervention Network (HAPIN) trial

Introduction Approximately 3-4 billion people worldwide are exposed to household air pollution (HAP) from burning solid fuels. HAP has been linked to increased blood pressure (BP) in pregnant women, although the literature is sparse and inconsistent. Methods We recruited 3195 pregnant women in Guatemala, India, Peru, and Rwanda and randomly assigned half of them to receive a liquified petroleum gas (LPG) stove/fuel intervention over the pregnancy, while those in the control group continued cooking with solid fuels. We measured gestational BP and personal exposure to PM2.5, black carbon (BC), and carbon monoxide (CO) three times during gestation: once at baseline and twice post-randomization. We conducted an intention-to-treat (ITT) analysis and an exposure-response analysis to determine if exposure to HAP during gestation was associated with an increase in BP at the final measurement compared to baseline. Results In the intervention group, 24-hour PM2.5 dropped from 84 μg/m3 at baseline to 24 μg/m3 after the intervention; BC and CO decreased similarly. ITT analyses showed an increase over gestation (as expected) in systolic BP (SBP) and diastolic BP (DBP) in both arms, but the increase was greater in the intervention group for SBP (0.69 mmHg, 95% CI 0.03 - 1.35) and DBP (0.62 mmHg, 95% CI 0.05 - 1.19) than controls. Exposure-response analyses showed that higher HAP exposures were associated with modest increases in SBP and DBP, but none of these associations were significant. Conclusion We found a greater increase in BP over gestation in the intervention group in ITT analyses. This was contrary to what we expected, though the increases were not considered clinically significant. In exposure-response analyses, we found a slight increase in BP with higher exposure, although no increases were significant. Overall, the LPG stove/fuel intervention did not markedly affect gestational BP. Keywords: Household Air Pollution, Blood Pressure, Pregnant Women