Background: To evaluate the differences in pregnancy outcomes between assisted reproductive technology (ART) patients and natural pregnant women in Shanghai, China in the past 6 years objectively. And to assess the feasibility of the research method of registry-database linkage in mainland China. Methods: This retrospective study was conducted using registry-database linkage. A total of 8102 pregnancies with ART and 8096 parturients with spontaneous conception (SC) from 10 reproductive centers and 111 hospitals composed our retrospective study. The primary outcomes were the rates of obstetric complications (pregnancy-induced hypertention [PIH], gestational diabetes mellitus [GDM], placenta previa, mode of delivery, preterm birth [PTB], low birth weight [LBW], and macrosomia). The prenatal outcomes were compared between ART and SC parturients, frozen-thawed embryo transfer (FET) and fresh embryo transfer, and in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). We calculated odds ratios (ORs) and 95% confidence intervals (CIs). Results: The final matching rate of the target population was 92% by using registry linkage. ART resulted in a higher rate of multiple birth, PTB, LBW, cesarean section, placenta previa and GDM compared with SC in the singleton cohort. In ART patients, pregnant women with FET had a significantly higher risk of PIH than those with fresh embryo transfer (14.1% Vs 9.3%, AOR1.528, 95% CI 1.303–1.793), but there was no difference between IVF and ICSI. FET is also related to the severity of PIH. Conclusions: ART increased the rate of complications during pregnancy, the risk and severity of PIH in patients with FET was higher than that in patients with fresh embryo transfer. The registry-database linkage study is an objective and feasible research method in mainland China.

Women with advanced maternal age (AMA) face a significant decline in embryo euploidy rates, leading to reduced fertility and increased risks of adverse pre

Background: Despite significant progress in assisted reproductive technology, in vitro fertilization (IVF) pregnancy rates remain suboptimal. Although the vaginal microbiome has been implicated in IVF outcomes, prior studies often overlooked embryonic aneuploidy, a major confounder. This study aimed to investigate the association between the vaginal microbiome and pregnancy outcomes in euploid embryo transfer cycles. Methods: This prospective study included 109 single euploid blastocyst transfer cycles. Upper vaginal swabs were collected on the transfer day and subjected to 16S rRNA gene sequencing. Microbial α- and β-diversity, community state types (CSTs), and differentially abundant taxa were compared between the clinical pregnancy (CP, n = 55) and non-clinical pregnancy (NCP, n = 54) groups. Results: The NCP group exhibited significantly higher vaginal microbial richness (Chao1, p = 0.029; ACE, p = 0.029) and distinct β-diversity compared with the CP group (R² = 0.049, p = 0.002), whereas CST distribution did not differ between groups. Within the non-Lactobacillus-dominant CST-IV subgroup, the CP group was relatively enriched in Bifidobacteriaceae (LDA = 5.0) with predicted fermentative pathways, whereas the NCP group showed higher relative abundances of Prevotella (LDA = −4.1), Dialister (LDA = −3.6), and Peptoniphilus (LDA = −2.3), accompanied by predicted tryptophan degradation and oxidative stress pathways. Discussion: These findings, derived mainly from computational prediction, suggest that fine-scale taxonomic and functional composition, rather than broad CST classification, may influence pregnancy outcomes following euploid embryo transfer, offering preliminary insights for microbiome-informed strategies to optimize reproductive outcomes. Future longitudinal studies incorporating shotgun metagenomics and metabolomics in independent cohorts are warranted to validate these preliminary observations and to clarify the dynamic association between vaginal microbiota and IVF pregnancy outcomes.