Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200135, PR China; Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai 200135, PR China.
Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, PR China.
Environ Int. 2022 Apr;162:107181. doi: 10.1016/j.envint.2022.107181. Epub 2022 Mar 15.
Ambient air pollution has adverse effects on the reproductive system. However, inconsistent conclusions were reached from different studies with regard to air pollutants and pregnancy outcomes, especially the livebirth rate in assisted reproductive technology (ART) in different windows of exposure.
A retrospective cohort study was conducted on 12,665 women who underwent first fresh or frozen embryo transfer cycle in the Yangtze River Delta of China. Daily average levels of six air pollutants in four different periods were obtained: Period 1 and 2: 90 days or one year prior to oocyte retrieval; Period 3 and 4: the day of oocyte retrieval or one year prior to oocyte retrieval to the day of serum hCG test or to the end of the pregnancy. A multiple logistic regression model was used to investigate the association between air pollutant exposure and pregnancy outcomes. Stratified analyses were conducted to explore potential modifier effects.
The one year exposure window (Period 2) before oocyte retrieval had a more evident negative association with pregnancy outcomes. Each IQR increase in ambient PM (OR: 0.89, 95% CI: 0.84-0.93), PM (OR: 0.82, 95% CI: 0.77-0.87), SO (OR: 0.87, 95% CI: 0.83-0.91) and CO (OR: 0.91, 95% CI: 0.87-0.96) was associated with a respective 11%, 18%, 13% and 9% decrease in the likelihood of live birth. In entire exposure window of Period 4, all air pollutants except for O were associated with a decreased likelihood of live birth. Stratified analyses showed that women undergoing frozen embryo transfer cycles, especially those with two embryos transferred, were more vulnerable to air pollutant exposure.
This study indicates a negative association between air pollutant exposure before oocyte retrieval and livebirth rate in ART. The adverse impact was more evident in one year exposure compared to three-month refresh cycle of the gametes. Additional protection from air pollution should be undertaken at least one year before ART, particularly for those with frozen embryo transfer cycles.
环境空气污染对生殖系统有不良影响。然而，不同研究对于空气污染物与妊娠结局之间的关系得出的结论并不一致，尤其是在辅助生殖技术（ART）中不同暴露窗口期的活产率。
本研究对在中国长江三角洲地区进行首次新鲜或冷冻胚胎移植周期的 12665 名女性进行了回顾性队列研究。获得了四个不同时期的六种空气污染物的日平均水平：时期 1 和 2：取卵前 90 天或一年；时期 3 和 4：取卵当天或取卵前一年至血清 hCG 检测日或妊娠结束日。采用多因素逻辑回归模型探讨了空气污染物暴露与妊娠结局之间的关系。进行了分层分析以探讨潜在的修饰效应。
取卵前一年的暴露窗口（时期 2）与妊娠结局的负相关更为明显。每增加一个 IQR 的环境 PM（比值比：0.89，95%置信区间：0.84-0.93）、PM（比值比：0.82，95%置信区间：0.77-0.87）、SO（比值比：0.87，95%置信区间：0.83-0.91）和 CO（比值比：0.91，95%置信区间：0.87-0.96）与活产率降低分别相关 11%、18%、13%和 9%。在整个时期 4 的暴露窗口中，除 O 外，所有空气污染物均与活产率降低相关。分层分析表明，接受冷冻胚胎移植周期的女性，尤其是移植两个胚胎的女性，更容易受到空气污染物暴露的影响。
本研究表明，取卵前的空气污染物暴露与 ART 中的活产率呈负相关。与配子的三个月刷新周期相比，一年的暴露对不良影响更为明显。ART 前至少一年应采取额外的空气污染保护措施，尤其是对于接受冷冻胚胎移植周期的女性。
