Excessive temperatures during pregnancy may cause low birth weight - study

A team led by researchers from Bar-Ilan University found a correlation between exposure to extreme temperatures during pregnancy and abnormally low birth weight.

womb 88.224 (photo credit: wikipedia)
womb 88.224
(photo credit: wikipedia)

Exposure to excessive heat or cold during pregnancy can result in low birth weight, according to a study published Wednesday in Environmental Health Perspectives.

The study was conducted by researchers from Bar-Ilan University in conjunction with the University of Haifa, Ben-Gurion University, the Israel Meteorological Service and several Spanish institutions.

Predicted mean term birthweight (tBW) as a function of the entire pregnancy average of the daily mean temperature (°C), for every climatic zone (A-C) and (D) combined with percentiles calculated by the climatic zone. (credit: DR. KEREN AGAY-SHAY/BAR-ILAN UNIVERSITY)Predicted mean term birthweight (tBW) as a function of the entire pregnancy average of the daily mean temperature (°C), for every climatic zone (A-C) and (D) combined with percentiles calculated by the climatic zone. (credit: DR. KEREN AGAY-SHAY/BAR-ILAN UNIVERSITY)

The researchers analyzed 624,940 births in Israel over five years and found that fetal growth was inhibited by exposure to extreme high and low temperatures, especially exposure to heat during the second and third trimesters of pregnancy.

After gathering and modeling data on the births and outdoor temperatures recorded during the pregnancies, the team conducted a statistical analysis and compared the temperatures to birthweight. They found a correlation between exposure to extreme temperatures and abnormally low birth weight.

“Our study demonstrated the significant associations between exposure to high and low outdoor temperature and birthweight in all term births born in Israel during five years," said Dr. Keren Agay-Shay, Director of the HER Lab at Bar-Ilan University's Azrieli Faculty of Medicine. "Lower birthweight may indicate abnormalities in intrauterine growth and is a risk factor for morbidity during early childhood and over the entire life course."

The researchers noted that health organizations must develop strategies in order to address these findings, especially as global temperatures increase due to climate change.