Exposure to high and low temperatures during pregnancy may result in reduced fetal growth (IMAGE)
Caption
An Israeli nation-wide study of more than 600,000 births, led by a researcher at Bar-Ilan University's Azrieli Faculty of Medicine, reveals consistent links between high and low temperatures and low fetal birth weight, particularly exposure to heat during the second and third trimesters. Published in the journal Environmental Health Perspectives, the study evaluates critical windows of susceptibility to extreme low and high temperatures during pregnancy and fetal growth in a nationwide cohort of 624,940 singleton term births in Israel during the period 2010-2014. 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. The tick marks on the x-axis are observed data points. The y-axis represents the smooth predicted estimated tBW. Shaded areas indicate the 95% confidence intervals. tBW-term mean birthweight (mean birthweight among births after 36 weeks of gestational age); Estimated predicted mean birthweight by average temperature during pregnancy by climatic zone: A) Mediterranean (Köppen classification Csa: temperate climate, dry and hot summer, N=562,708; 11,377 sq km); B) Steppe/semi-arid (combining Köppen classifications BSh and BSk for areas characterized by dry, hot and cold temperatures, respectively, BSh/k, N= 56,066; 6,188 sq km); C) Desert/arid (combining Köppen classifications BWh and BWk, also characterized by dry, hot and cold temperatures, respectively, BWh/k, N=6,166, 10,753 sq km).
Credit
Dr. Keren Agay-Shay, Bar-Ilan University
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