National Human Genetic Resources Center, Beijing, China; National Research Institute for Family Planning, Beijing, China.
National Human Genetic Resources Center, Beijing, China; Department of Maternal and Child Health, School of Public Health, Peking University, Beijing, China; Center for Reproductive Medical, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China.
Environ Int. 2020 Sep;142:105851. doi: 10.1016/j.envint.2020.105851. Epub 2020 Jun 22.
Little is known about the effect of ambient temperature on preterm birth, especially for the trimester-specific effects.
To evaluate whether exposure to relatively low or high temperature during pregnancy is associated with increasing risk of preterm birth or not.
We analysed the data of a birth cohort with 1,281,859 singleton pregnancies during 2013-2014 and matched the home address of each pregnant women to the model based daily meteorological and air pollution data. Then we used the Cox proportional hazard regression models with random effect to estimate the non-linear associations between exposure to relatively low or high temperature at each trimester of pregnancy and the risk of preterm birth, after controlling for air pollution and individual-level covariates.
The overall preterm birth rate was 8.1% (104,493 preterm births). Exposure to relatively low or high temperatures during the entire pregnancy significantly increase the risk of preterm birth, with hazard ratios (HRs) [95% confidence intervals (CIs)] of 1.03 (95%CI: 1.02, 1.04) for relatively low (9.1 ℃, the 5th percentile) temperature and 1.55 (95%CI: 1.48, 1.61) for relatively high (23.0 ℃, the 95th percentile) temperature in comparison with the thresholds (12.0 ℃). Pregnant women at the early pregnancy (the 1 and 2 trimester) are more susceptible to high temperatures while pregnant women at the late pregnancy (the 3 trimester) are more susceptible to low temperatures.
These findings provide new evidence that exposure to relatively low or high temperatures during pregnancy increases the risk of preterm birth, which can serve as scientific evidence for prevention of preterm birth.
关于环境温度对早产的影响知之甚少，尤其是关于每个孕期的具体影响。
评估孕妇在妊娠期间暴露于相对较低或较高温度是否与早产风险增加有关。
我们分析了 2013-2014 年期间一个 1,281,859 例单胎妊娠队列的数据，并将每位孕妇的家庭住址与基于模型的每日气象和空气污染数据相匹配。然后，我们使用具有随机效应的 Cox 比例风险回归模型，在控制空气污染和个体水平协变量后，估计妊娠每个孕期暴露于相对较低或较高温度与早产风险之间的非线性关系。
总体早产率为 8.1%（104,493 例早产）。整个孕期暴露于相对较低或较高温度会显著增加早产风险，相对较低（9.1℃，第 5 百分位数）和相对较高（23.0℃，第 95 百分位数）温度的危险比（HRs）[95%置信区间（CI）]分别为 1.03（95%CI：1.02，1.04）和 1.55（95%CI：1.48，1.61）。与阈值（12.0℃）相比。妊娠早期（第 1 和第 2 孕期）的孕妇对高温更敏感，而妊娠晚期（第 3 孕期）的孕妇对低温更敏感。
这些发现提供了新的证据，表明孕妇在妊娠期间暴露于相对较低或较高温度会增加早产风险，这可为预防早产提供科学依据。
