Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, University of Arizona, 1295 N. Martin Ave, PO Box 245211, Tucson, AZ, 85724, USA.
Department of Mathematics & Statistics, Amherst College, Amherst, MA, USA.
J Assist Reprod Genet. 2020 Oct;37(10):2427-2433. doi: 10.1007/s10815-020-01915-2. Epub 2020 Aug 13.
It is known that delivery rates from spontaneous conception vary according to season which may be due to cultural or environmental factors; however, conflicting data exist regarding whether outcomes from IVF are also seasonally dependent. The present study was designed to test the hypothesis that the season at oocyte retrieval is associated with livebirth after fresh transfer.
Dates of oocyte retrieval for all autologous cycles in our IVF program between January 2012 and December 2017 were categorized by season. Dates were linked to local temperature (min, max, average) and day length obtained from meteorological records. Average maximum temperature and day length were categorized into tertiles. Multivariable logistic regression, adjusted for age and quadratic age, were used to model odds (aOR) of implantation, clinical pregnancy, spontaneous abortion, and livebirth.
Patient characteristics were similar across seasons. As expected, temperature and day length varied by season. When compared with cycles started during winter, there was no difference in the age-adjusted odds of livebirth for the other three seasons (spring: aOR: 0.97, 95% CI: 0.82-1.13; summer: aOR: 1.05, 0.90-1.23; fall: aOR: 0.98, 0.84-1.15). There was a positive linear trend between temperature and odds of implantation, and clinical pregnancy (p value, test for linear trend (implantation, p = 0.02; clinical pregnancy, p = 0.01)) but no association with livebirth for temperature or day length.
We found that season at oocyte retrieval was not associated with livebirth, contrary to patterns seen in naturally conceived populations. However, our data did suggest modestly higher odds of clinical pregnancy for retrievals in June and July, and that higher temperature at time of retrieval was associated with higher odds of clinical pregnancy but not livebirth.
众所周知，自然受孕的分娩率因季节而异，这可能与文化或环境因素有关；然而，关于 IVF 的结果是否也受季节影响，目前还存在相互矛盾的数据。本研究旨在检验卵母细胞采集时的季节与新鲜胚胎移植后活产之间是否存在关联的假设。
我们的 IVF 项目中，2012 年 1 月至 2017 年 12 月期间所有自体周期的卵母细胞采集日期均按季节分类。这些日期与气象记录中的当地温度（最低、最高、平均）和日长相关联。平均最高温度和日长分为三分位。采用多变量逻辑回归，调整年龄和二次年龄，对植入、临床妊娠、自然流产和活产的优势比（aOR）进行建模。
各季节患者特征相似。如预期的那样，温度和日长因季节而异。与冬季开始的周期相比，其他三个季节的活产年龄调整优势比没有差异（春季：aOR：0.97，95%CI：0.82-1.13；夏季：aOR：1.05，0.90-1.23；秋季：aOR：0.98，0.84-1.15）。温度与植入和临床妊娠的优势比呈正线性趋势（p 值，线性趋势检验（植入，p=0.02；临床妊娠，p=0.01）），但与活产无关。
我们发现，与自然受孕人群的模式相反，卵母细胞采集时的季节与活产无关。然而，我们的数据确实表明，6 月和 7 月采集的卵母细胞的临床妊娠优势略高，且采集时的温度较高与临床妊娠的优势比较高相关，但与活产无关。
