Association between temperature and maternal stress during pregnancy

Background: Maternal psychological stress during pregnancy has essentially been conceptualized as a teratogen. However, little is known about the effect of temperature on maternal stress during pregnancy. The aim of this study is to investigate the relationship between temperature and maternal stress during pregnancy. Methods: In 2010, a total of 1931 eligible pregnant women were enrolled across Shanghai from four prenatal care clinics during their mid-to-late pregnancy. Maternal life-event stress and emotional stress levels during pregnancy were assessed by the "Life Event Scale for Pregnant Women" (LESPW) and "Symptom Checklist-90 Revised Scale" (SCL-90-R), respectively. Exposure to ambient temperature was evaluated based on daily regional average in different moving average and lag days. The generalized estimating equations were used to evaluate the relationship between daily average temperature/temperature difference and maternal stress. Results: After adjusting for relevant confounders, an U-shaped relationship was observed between daily average temperature and maternal Global-Severity-Index (GSI) of the SCL-90-R. Cumulative exposures to extremely low temperatures (< P5, 1.4-10.5 degrees C, lag 0-1 days, 0-2 days and 0-5 days) and extremely high temperatures (a P95, 31.2-34.1 degrees C, lag 0-1 days and 0-2 days), and acute exposures to extremely low (lag day 0, 1, 2 and 3) and high (lag day 0, 1) temperatures, all induced higher risks of high GSI (the highest tertile), compared to the risk induced by exposed to an optimal temperature range (20-25 degrees C) (P < 0.05). Increased temperature difference was associated with high maternal GSI (P < 0.05). However, non-significant associations were observed between daily average temperatures/temperature differences and maternal log-transferred LESPW scores. Conclusions: Cumulative and acute exposures to extremely low/high temperatures may both induce emotional stress during pregnancy.