Program in Public Health & Department of Planning, Policy, and Design, University of California at Irvine, Irvine, CA.
Center for Health Equity Studies, Stockholm University, Sweden.
Ann Epidemiol. 2014 Feb;24(2):116-21. doi: 10.1016/j.annepidem.2013.11.005. Epub 2013 Nov 15.
Although the literature reports adverse birth outcomes following ambient heat, less work focuses on cold. We, moreover, know of no studies of cold that examine stillbirth. We tested the relation between cold ambient temperature during pregnancy in Sweden and four outcomes: stillbirth, preterm, birth weight for gestational age, and birth length. We examined births from 1915 to 1929 in Uppsala, Sweden, which-unlike most societies today-experienced substandard indoor-heating and fewer amenities to provide shelter from cold.
We retrieved data on almost 14,000 deliveries from the Uppsala Birth Cohort Study. We linked a validated, daily ambient temperature series to all pregnancies and applied Cox proportional hazards (stillbirth and preterm) and linear regression models (birth weight and length). We tested for nonlinearity using quadratic splines.
The risk of stillbirth rose as ambient temperature during pregnancy fell (hazard ratio for a 1°C decrease in temperature, 1.08; 95% confidence interval, 1.00 to 1.17). Cold extremes adversely affected preterm and birth length, whereas warm extremes increased preterm risk. We observed no relation between cold and birth weight for gestational age.
In historical Sweden, cold temperatures during pregnancy increased stillbirth and preterm risk and reduced birth length among live births.
尽管文献报道了环境热对不良出生结局的影响，但对冷的关注较少。此外，我们不知道有任何研究关注寒冷对死产的影响。我们检验了瑞典妊娠期间环境温度与以下四个结果的关系：死产、早产、胎龄体重和出生体长。我们研究了瑞典乌普萨拉市 1915 年至 1929 年的出生情况，与当今大多数社会不同，那里的室内供暖标准较低，提供避寒设施的设施也较少。
我们从乌普萨拉出生队列研究中检索了近 14000 次分娩的数据。我们将经过验证的每日环境温度序列与所有妊娠联系起来，并应用 Cox 比例风险（死产和早产）和线性回归模型（胎龄体重和体长）。我们使用二次样条检验非线性关系。
随着妊娠期间环境温度的降低，死产风险增加（温度每降低 1°C 的风险比为 1.08；95%置信区间为 1.00 至 1.17）。极端寒冷会对早产和出生体长产生不利影响，而极端温暖会增加早产风险。我们没有观察到寒冷与胎龄体重之间的关系。
在历史上的瑞典，妊娠期间的低温会增加死产和早产风险，并降低活产儿的出生体长。
