During a Heat wave being pregnant for a woman is far from ideal scenario, but new research in such extreme temperatures can do more than one finds uncomfortable expectant mothers; they may increase the risk of preterm birth.
In a study published in the journal Environmental Health Perspectives, Health (NIH), researchers from the National Institutes of pregnancy increased by up to a fifth of women at risk of preterm birth to extreme cold or intense heat exposure Found.
According to the Centers for Disease Control and Prevention (CDC), in 2014, around 1 in 10 infants in the United States were born preterm – defined as the birth of a baby before 37 weeks of pregnancy.
Preterm birth is the leading cause of infant death in the U.S., and it is also a primary cause of long-term disabilities and neurological disorders, such as cerebral palsy and developmental delay.
Known risk factors for preterm birth, preterm delivery, smoking, alcohol, and drug use, such as urinary tract infections and high blood pressure, certain medical conditions, including a history, a number of are.
Now, senior author Pauline Mendola, Ph.D., of the NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), and colleagues suggest extreme temperatures could also be a risk factor for preterm birth and early birth – delivery at between 37-38 weeks of pregnancy.
Mendola and team reached their findings by analyzing the medical records of 223,375 women from 12 medical centers across the U.S. who gave birth between 2002-2008. All women had singleton deliveries.
These data were then linked with hourly temperature data – obtained from the Weather Research and Forecasting Model – for the regions surrounding each of the 12 medical centers, in order to determine whether temperatures influenced the women’s risk of preterm birth.
For the study, the extreme heat temperatures above the 90th percentile were defined as mild temperatures, 10-90th percentile was defined as between the 10th percentile of the extreme cold, as defined below had gone.
The first 7 weeks of pregnancy in women who were exposed to mild temperatures, compared with 20 percent of those who were exposed to extreme cold more likely to give birth before 34 weeks of pregnancy was more than 9 percent in 34-36 were more likely to give birth this week, and 3 percent more likely to give birth at 37-38 weeks.
Women exposed to extreme heat in the first 7 weeks of pregnancy were 11 percent more likely to give birth before 34 weeks and 4 percent more likely to deliver at 37-38 weeks, compared with those exposed to mild temperatures.
The link between extreme cold and preterm birth diminished after 7 weeks, though exposure to extreme heat at 8-14 weeks of pregnancy increased women’s risk of giving birth at 37-38 weeks by 4 percent.
Additionally, the researchers found women exposed to extreme heat between 15-21 weeks of pregnancy were 18 percent more likely to give birth at 34 weeks and between 34-36 weeks, and they were 4 percent more likely to give birth at weeks 37-38.
The researchers are unable to conclude why exposure to extreme cold after 7 weeks of pregnancy did not increase preterm birth risk, but they suggest it is because the effects of cold weather are easier to escape – through seeking shelter, for example – while extreme heat is harder to avoid.
While it is unclear why extreme cold and heat appear to affect preterm birth risk, the team speculates that extreme temperatures might impair placental development or blood flow to the uterus, which can trigger early labor.
The researchers say further studies, the risk of preterm birth, how extreme temperatures to gain a better understanding of these findings present a warning for pregnant women and health care providers must act as needed.