BETHESDA, Md., Aug. 31 (UPI) -- Some women are more sensitive to temperature during pregnancy, but researchers report in a recent study that pregnant women exposed to extreme temperatures -- hot or cold -- can be affected beyond issues of comfort.
Researchers at the Nationals Institutes of Health linked exposure to extreme temperatures during the first seven weeks of pregnancy to increased risk for preterm birth, as well as prolonged exposure to extreme heat, according to a study published in the journal Environmental Health Perspectives.
Previous studies have linked extreme temperatures to preterm birth and complications for newborns as a result of extreme hot and cold, with some pegging the increased risk to environmental shifts caused by global climate change.
In the new study, NIH researchers echo the sentiment of others that global climate change may lead to more extreme swings in temperature, increasing the potential exposure of pregnant women who need to be advised of the risk.
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"Our findings indicate that it may well be prudent to minimize the exposure of pregnant women to extremes in temperature," Dr. Pauline Mendola, an epidemiologist in the Division of Intramural and Population Health Research at the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development and lead author of the study, said in a press release.
For the study, NIH researchers analyzed medical records from 223,375 single-child deliveries, linking them to the mother's exposure to extreme hot or cold temperature based on average temperatures near the hospitals babies were born at.
The researchers found that women exposed to extreme cold during the first seven weeks of pregnancy were at a 20 percent higher risk of giving birth before 34 weeks of gestation, 9 percent increased risk to give birth between weeks 34 and 36 and 3 percent more likely to give birth in weeks 37 or 38.
For women exposed to extreme heat during the first seven weeks of pregnancy, the risk for birth before 34 for weeks increased by 11 percent and for birth at weeks 37 or 38 increased by 4 percent.
Extreme heat exposure throughout a pregnancy, however, was found to increase preterm birth considerably. Women exposed to heat during weeks 15 and 21 of pregnancy had an 18 percent increased risk of birth at weeks 34 to 36 and a 4 percent increased risk for birth at weeks 37 to 39. Heat exposure during weeks 8 and 14 of pregnancy also increased risk for preterm birth at week 37 or 38 by 4 percent.
Overall, the exposure to heat throughout a pregnancy increased preterm birth by 6 to 21 percent, researchers reported.
While the researchers say in the study that the effects of climate change may increase the risk for preterm birth because of environmental variation, they also say more research is needed to understand how temperature affects the risk.
