Department of Public Health, Guangdong Women and Children Hospital, Guangzhou, China.
Department of Obstetrics, Guangdong Women and Children Hospital, Guangzhou, China.
Front Public Health. 2023 Jul 27;11:1156880. doi: 10.3389/fpubh.2023.1156880. eCollection 2023.
Prior literature has found that extreme temperature exposure is associated with preterm birth (PTB). However, current evidence provides heterogeneous conclusions, and data on extreme cold and across different pre-pregnancy body mass index (BMI) statuses are limited.
We conducted a population-based retrospective cohort of 251,257 women between 2014 and 2017 in Guangdong, China, to evaluate whether the association between extreme temperature exposure and PTB varied in pre-pregnancy BMI status. Participants were divided into three categories based on pre-pregnancy BMI: underweight (BMI < 18.5 kg/m), normal weight (18.5-23.9 kg/m), overweight or obesity (≥ 24.0 kg/m). We fitted Cox proportional hazards models to assess the association between daily mean temperature and PTB at each trimester for each BMI category separately. The hazard ratios (HRs) at the 5th and 95th percentiles of temperature (defined as low and high temperatures respectively) were provided using the median temperature at each trimester as a reference.
58,220 (23.2%) were underweight, and 27,865 (11.1%) were overweight or obese. Of the 251,257 women, 18,612 (7.41%) had PTB delivery. Both low-and high-temperature exposure increased the risk of PTB in the third trimester, while cold exposure mostly mitigated the risk for the first and second trimesters. The association with low temperature was the strongest in the third trimester, especially for underweight women (HR: 1.825; 95%CI: 1.529 ~ 2.179), while the association with high temperature was the strongest also in the third trimester, especially for obese or overweight women (HR:1.825; 95%CI:1.502 ~ 2.218). Furthermore, the attributable fractions of PTB risk in the third trimester were estimated as 5.59% (95% CI: 3.58, 7.98%) for cold exposure among underweight women and 3.31% (95% CI: 2.01, 4.88%) for hot exposure among overweight or obese women.
Exposure to either low temperature in the third trimester or high temperature during pregnancy was associated with a higher risk of PTB. Moreover, pre-pregnancy BMI status might affect the susceptibility of pregnant women. Such findings would be useful to develop targeted measures for vulnerable populations.
先前的研究表明，极端温度暴露与早产（PTB）有关。然而，目前的证据得出了不一致的结论，并且关于极寒天气和不同孕前体重指数（BMI）状态的数据有限。
我们在中国广东进行了一项基于人群的回顾性队列研究，纳入了 2014 年至 2017 年间的 251257 名女性，以评估孕前 BMI 状态是否会影响极端温度暴露与 PTB 之间的关联。参与者根据孕前 BMI 分为三类：体重过轻（BMI<18.5kg/m²）、正常体重（18.5-23.9kg/m²）、超重或肥胖（≥24.0kg/m²）。我们使用 Cox 比例风险模型分别评估了每个 BMI 类别在每个孕期 trimester 中，每日平均温度与 PTB 之间的关联。使用每个孕期 trimester 的中位温度作为参考，提供了温度第 5 百分位和第 95 百分位（分别定义为低温和高温）的危险比（HR）。
58220 名（23.2%）女性体重过轻，27865 名（11.1%）女性超重或肥胖。在 251257 名女性中，有 18612 名（7.41%）发生了 PTB 分娩。低温和高温暴露均增加了第三孕期 PTB 的风险，而寒冷暴露主要减轻了第一和第二孕期的风险。低温暴露与第三孕期的关联最强，尤其是体重过轻的女性（HR：1.825；95%CI：1.529-2.179），而高温暴露与第三孕期的关联也最强，尤其是超重或肥胖的女性（HR：1.825；95%CI：1.502-2.218）。此外，体重过轻的女性中，第三孕期寒冷暴露导致 PTB 风险的归因分数估计为 5.59%（95%CI：3.58%，7.98%），超重或肥胖的女性中，第三孕期高温暴露导致 PTB 风险的归因分数估计为 3.31%（95%CI：2.01%，4.88%）。
第三孕期的低温暴露或孕期的高温暴露均与 PTB 风险增加相关。此外，孕前 BMI 状态可能会影响孕妇的易感性。这些发现有助于为脆弱人群制定有针对性的措施。
