UCSF

Background: Approximately 3.8 billion people in low- and middle-income countries use unclean fuels as a source of primary cooking fuel as well as for heating. For pregnant women, the toxic chemicals produced by combustion of unclean fuels not only affect women’s health directly, but particulate matter and carbon monoxide are absorbed in maternal blood and cross the placental barrier potentially affecting the fetus. Methods: This dissertation presents three manuscripts. The first is a systematic review examining birth outcomes related to household air pollution (HAP) from type of cooking fuel in low-and middle-income countries. PRISMA 2009 guidelines were used for this systematic review. The inclusion criteria were quantitative, peer reviewed journal articles published within a date range of May 1, 2013-June 12, 2021. The quality of available evidence was evaluated using the Office of Health Assessment and Translation (OHAT) risk of bias rating tool. The reviewed studies presented evidence for an increased risk of low birth weight (LBW), preterm birth (PTB), small for gestational age (SGA), stillbirth, neonatal mortality and reduction in birthweight with unclean fuel use compared to cleaner fuels. The second study’s objective was to evaluate the effects of a liquefied petroleum gas (LPG) stove and fuel intervention during pregnancy on congenital anomalies, stillbirth and neonatal mortality using data from the Household Air Pollution Intervention Network (HAPIN) Trial. The HAPIN trial is a randomized controlled trial of LPG stoves and fuel distribution in nearly 3200 households conducted across India, Guatemala, Peru and Rwanda. Participants in the HAPIN Trial were monitored for adverse and serious adverse events. All analyses were performed according to intention-to-treat (ITT) analysis, and binary outcomes of congenital anomalies, stillbirth and neonatal mortality were compared between the two arms using log binomial models. The third study’s objective was to evaluate the effects of a LPG stove and fuel intervention during pregnancy on maternal outcomes of spontaneous abortion, postpartum hemorrhage, hypertensive disorders of pregnancy, and maternal mortality using data from the Household Air Pollution Intervention Network (HAPIN) Trial. All analyses were performed according to intention-to-treat (ITT) analysis, and binary outcomes of spontaneous abortion, postpartum hemorrhage, preeclampsia/eclampsia, and maternal mortality were compared between the two arms using log binomial models. Results: Systematically reviewing the evidence and risk of bias ratings illuminated several gaps in the current literature related to exposure assessment, outcome measurement and adequacy of adjustment for confounding. Results for the second study showed that adverse fetal and neonatal outcomes (congenital anomalies, stillbirth, neonatal mortality) did not differ based on stove type across four country research sites. Pregnant women assigned to the LPG intervention arm had a slightly lower risk of congenital anomaly (RR 0.96, 95% CI: 0.55, 1.70) and neonatal mortality (RR 0.97, 95% CI: 0.53, 1.77) compared to women in the control arm. In regards to stillbirth, pregnant women assigned to the LPG intervention arm had a slightly higher risk of stillbirth (RR 1.01, 95% CI: 0.60, 1.70) compared to women in the control arm. However these results were not statistically significant even after adjusting for maternal education, household food insecurity and bank account. Results for the third study demonstrated adverse maternal outcomes (spontaneous abortion, hypertensive disorders of pregnancy, postpartum hemorrhage and maternal mortality) did not differ based on stove type across the four country research sites. In intention-to-treat analyses we found women assigned to the LPG intervention arm had a higher risk of spontaneous abortion (RR 2.69, 95% CI: 0.71, 10.12) and maternal mortality (RR 1.51, 95% CI: 0.25, 9.03) compared to women in the control arm. Pregnant women assigned to the LPG intervention arm had a lower risk of postpartum hemorrhage (RR 0.84, 95% CI: 0.26, 2.74) and hypertensive disorders of pregnancy (RR 0.84, 95% CI: 0.26, 2.74) compared to women in the control arm. However all results were not statistically significant even after adjusting for maternal education, household food insecurity and bank account. Conclusion: The systematic review presented evidence for an increased risk of LBW, PTB, SGA, stillbirth, neonatal mortality and reduction in birthweight with solid fuel and kerosene use compared to cleaner fuels like gas and LPG. The HAPIN trial was the first multi-country RCT collecting data on household air pollution and health outcomes on pregnant women across four countries. While the LPG stove intervention did not significantly reduce the relative risk of adverse birth outcomes, women assigned to the LPG intervention arm had a slightly lower risk of congenital anomaly, neonatal mortality, hypertensive disorders of pregnancy and postpartum hemorrhage compared to women in the control arm. Access to sustainable and affordable energy should remain a priority for the global community.