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Background Previous studies have focused on pregnancy outcomes after frozen embryo transfer (FET) performed using different endometrial preparation protocols. Few studies have evaluated the effect of endometrial preparation on pregnancy-related complications. This study was designed to explore the association between different endometrial preparation protocols and adverse obstetric and perinatal complications after FET. Methods We retrospectively included all FET cycles (n = 12,950) in our hospital between 2010 and 2017, and categorized them into three groups, natural cycles (NC), hormone replacement therapy (HRT) and ovarian stimulation (OS) protocols. Pregnancy-related complications and subsequent neonatal outcomes were compared among groups. Results Among all 12,950 FET cycles, the live birth rate was slightly lower for HRT cycles than for NC (HRT vs. NC: 28.15% vs. 31.16%, p p p = 0.001). Among 3864 women with live birth, preparing the endometrium using OS or HRT protocols increased the risk of preeclampsia, and intrahepatic cholestasis of pregnancy (ICP) in both singleton and multiple deliveries. Additionally, OS and HRT protocols increased the risk of low birth weight (LBW) and small for gestational age (SGA) in both singletons and multiples after FET. Conclusion Compared with HRT or OS protocols, preparing the endometrium with NC was associated with the decreased risk of pregnancy-related complications, as well as the decreased risk of LBW and SGA after FET.

Background: As a growing health problem, maternal obesity may have an adverse effect on offspring neurodevelopment. The effects of maternal overweight and obesity and excessive gestational weight gain on offspring intelligence remains unclear. This meta-analysis aimed to assess the influence of prepregnancy body mass index (BMI) and gestational weight gain on children’s intelligence.Methods: We systematically searched PubMed, Embase, Cochrane Library and Ovid Medline from their inception through July 2020. Studies assessing the association between prepregnancy BMI or gestational weight gain and children’s intelligence (from 3 years to 10 years) were screened manually before final inclusion. We included prospective and retrospective cohorts that analysed the association between prepregnancy BMI or gestational weight gain and intelligence of offspring. We used the Mantel-Haenszel fixed-effects method to compute the weight mean difference (WMD) and 95% confidence interval (CI) of each study.Results: Twelve articles were included in the systematic review, and six of them were included in the meta-analysis. There was a significant full-scale IQ reduction in children of overweight and obese women, with WMDs of -3.25 (95% CI: -3.05, -2.42) and -4.85 (95% CI: -5.93, -3.76), respectively. Compared with that in the control group, the WMDs for performance IQ were -2.40 (95% CI: -3.45, -1.34) and -5.28 (95% CI: -7.22, -3.34) in the overweight and obesity groups, respectively, and the WMDs for verbal IQ were -3.47 (95% CI: -4.38, -2.56) and -5.71 (95% CI: -7.13, -4.29), respectively. However, there was no significant reduction in children’s full-scale intelligence scores due to excessive weight gain; the WMD was -0.14 (95% CI: -0.92, 0.65).Conclusions: Prepregnancy overweight and obesity might have disadvantageous consequences on children’s intelligence; however, we observed no significant difference between excessive and normal gestational weight gain. Therefore, weight control before pregnancy is more important than that during pregnancy in terms of children’s intelligence.Trial registration: This systematic review and meta-analysis have been registered in PROSPERO (Number: CRD42020199215).

While the effects of ambient pollutants on adverse perinatal outcomes have been studied, most studies have focused on preterm birth, stillbirth, and low birthweight. Few studies have examined the effects of ambient pollutants on prelabor rupture of membranes (PROM). This study was designed to explore the acute effects of ambient pollutants on both term PROM (TPROM) and preterm PROM (PPROM). We enrolled pregnant women receiving antenatal care between October 2013 and December 2019 at the International Peace Maternity and Child Health Hospital (IPMCHH). The effects of ambient pollutants (including PM2.5, PM10, SO2, CO, NO2, and 8-h O3) on TPROM and PPROM were estimated using generalized additive models (GAMs). Exposure-response relationship curves were also evaluated using GAMs after adjustment for confounding factors. Potential lagged effects were examined using various lag models. The data of 100,200 pregnant women who delivered at IPMCHH were analyzed. The fitted spline curves for PPROM were similar to the temporal trends of PM2.5, PM10, SO2, CO and NO2 but not O3, while those for TPROM were different from the temporal trends of all six air pollutants. An increased risk of PPROM was associated with increased concentrations of PM2.5, PM10, SO2 and CO on lag days 2 and 3, while no association was found between PPROM and daily concentration of O3. After adjustment for confounding factors, there was a shift in the exposure-response curves, indicating associations between PPROM and PM2.5, PM10, SO2, and CO on lag days 2-3. Interaction effects of PM2.5, PM10, SO2, and CO were also found to increase the risk of PPROM. In conclusion, acute exposures to six critical air pollutants were not associated with an increased risk of TPROM; however, PM2.5, PM10, SO2, and CO were found to interact, increasing the risk for PPROM on lag days 2 and 3.

Maternal supraphysiological estradiol (E2) environment during pregnancy leads to adverse perinatal outcomes. However, the influence of oocyte exposure to high E2 levels on perinatal outcomes remains unknown. Thus, a retrospective cohort study was conducted to explore the effect of high E2 level induced by controlled ovarian stimulation (COH) on further outcomes after frozen embryo transfer (FET). The study included all FET cycles (n = 10,581) between 2014 and 2017. All cycles were categorized into three groups according to the E2 level on the day of the human Chorionic Gonadotropin trigger. Odds ratios (ORs) and their confidence intervals (CIs) were calculated to evaluate the association between E2 level during COH and pregnancy outcomes and subsequent neonatal outcomes. From our findings, higher E2 level was associated with lower percentage of chemical pregnancy, clinical pregnancy, ongoing pregnancy, and live birth as well as increased frequency of early miscarriage. Preterm births were more common among singletons in women with higher E2 level during COH (aOR1 = 1.93, 95% CI: 1.22–3.06; aOR2 = 2.05, 95% CI: 1.33–3.06). Incidence of small for gestational age (SGA) was more common in both singletons (aOR1 = 2.01, 95% CI: 1.30–3.11; aOR2 = 2.51, 95% CI: 1.69–3.74) and multiples (aOR1 = 1.58, 95% CI: 1.03–2.45; aOR2 = 1.99, 95% CI: 1.05–3.84) among women with relatively higher E2 level. No association was found between high E2 level during COH and the percentage of macrosomia or large for gestational age. In summary, oocyte exposure to high E2 level during COH should be brought to our attention, since the pregnancy rate decreasing and the risk of preterm birth and SGA increasing following FET.