Heat Waves: Some Potential Effects of Climate Change on Abnormal Birth Outcomes and Adverse Maternal Health Conditions

Like other extreme weather events, heat waves are likely to occur more frequently worldwide as a consequence of climate change, and their impacts are likely to be borne disproportionately by developing countries. However, detailed data on health outcomes for developing countries over a sufficient period of time are not readily available. Instead, we use monthly panel data for more than 3000 U.S. counties, constructed from the confidential version of the U.S. Natality Files for 1989-2008. We investigate the effects of heat waves on adverse health conditions for babies and expectant mothers when these mothers have been exposed to heat waves during gestation or during the period just prior to conception. Rather than just birth weight and gestational age, we focus on less-common metrics such as abnormal conditions in the newborn (fetal distress, reliance on a ventilator, and meconium aspiration) and adverse health conditions in the mother (pregnancy-related hypertension, uterine bleeding during pregnancy, eclampsia, and incompetent cervix). Even within the U.S., where there is widespread access to air conditioning, heat waves increase the fraction of babies with abnormal conditions related to maternal stress, as well as the fraction of mothers who experience pregnancy-related adverse health conditions. The scope of these impacts in developing countries is likely to be even greater.