Heat Exposure During Pregnancy Linked to Severe Maternal Morbidity

MONDAY, Sept. 11, 2023 (HealthDay News) -- Long- and short-term heat exposure during pregnancy is associated with an increased risk for severe maternal morbidity (SMM), according to a study published online Sept. 7 in JAMA Network Open.

Anqi Jiao, from the University of California at Irvine, and colleagues conducted a retrospective population-based epidemiological cohort study at Kaiser Permanente Southern California, between Jan. 1, 2008, and Dec. 31, 2018, to examine the associations between long- and short-term maternal heat exposure and SMM. Data were included for 3,446 SMM cases among 403,602 pregnancies (0.9 percent).

The researchers observed significant associations between SMM and long-term heat exposure during pregnancy and during the third trimester. High exposure (≥80th percentile of the proportions) to extreme heat days during pregnancy and the third trimester were linked to increases in the risk for SMM (27 and 28 percent, respectively). Under all heatwave definitions, elevated SMM risks were significantly associated with short-term heatwave exposure. The magnitude of associations increased from the least to the most severe heatwave exposure (odds ratios, 1.32 to 2.39, respectively). Mothers with lower educational attainment and those whose pregnancies started in the cold season (November through April) had greater associations (odds ratios for high exposure to extreme heat days during pregnancy, 1.43 and 1.37, respectively).

"These results indicate the potential benefit of targeted interventions to reduce the risk of SMM by mitigating maternal heat exposure, especially among mothers with low socioeconomic status," the authors write.

One author disclosed ties to the biopharmaceutical industry.

Abstract/Full Text