An ongoing rise in global average temperatures may be causing a decrease in birth weight, a study showed Thursday.

According to a study by Lee Seung-jae, a graduate school student at Sogang University in Seoul, the average weight of newborns decreased 0.46 grams when their mothers were exposed to hotter temperatures during the second trimester.

“With average temperatures increasing 1 degree Celsius during the second trimester, birth weight decreased 0.46 grams on average,” wrote Lee in his study.

“An increase in temperature may lead to lower birth weight and a percentage increase in underweight babies,” he added.

Lee said he studied the weight of babies born between the 37th and 39th week of pregnancy from 1973 to 2000 and compared the infant birth outcomes with temperature change, precipitation and biological factors of the mothers. The study was based on data provided by the National Center for Health Statistics and National Climatic Data Center.

By the end of the century, birth weight may drop 2.2 grams on average and the percentage of underweight newborns could increase 0.04 percent, Lee says, if the global average temperature rises 4.8 degrees Celsius by 2100 as predicted by international climate scientists.

By Cho Chung-un (christory@heraldcorp.com)