OBJECTIVE: To explore the association between snoring and in vitro fertilization (IVF) outcomes in infertile women, focusing on embryological parameters and pregnancy outcomes. METHODS: This study represents a secondary analysis of the PKU-ERC study (NCT05373290). We included a cohort of 632 infertile women, aged 24-45 years, undergoing their first IVF treatment from the Reproductive Center of Peking University People's Hospital between January 2018 and November 2021. All patients with the assistance of their husbands completed a questionnaire including snoring status and frequency before ovulation induction (OI). Embryology parameters were evaluated during the first IVF cycle, and pregnancy outcomes were assessed through follow-up. RESULTS: Among 579 subjects, 33.5 % reported occasional snoring, and 8.8 % reported frequent snoring. After adjusting for confounding factors, multiple linear regression model showed that frequent snorers had higher β-coefficients for the number of blastocysts and available embryos compared to non-snorers (both P <
0.05). Among 551 subjects who completed the first embryo transfer, 6.2 % suffered biochemical pregnancy loss. Frequent snorers were more likely to experience biochemical pregnancy loss compared to non-snorers and occasional snorers (5.7 % vs. 14.6 %, P = 0.033
4.8 % vs. 14.6 %, P = 0.026). Multivariable analysis revealed that frequent snoring was a risk factor for biochemical pregnancy loss (adjusted odds ratio, aOR: 2.95, 95 % confidence interval, CI: 1.06-8.24, P = 0.039), while high-density lipoprotein cholesterol (HDL-C) level was a protective factor after IVF (aOR: 0.21, 95 % CI: 0.05-0.92, P = 0.038). CONCLUSION: Frequent snoring is associated with a decreased number of available oocytes and an increased risk of biochemical pregnancy loss following IVF. However, the potential influence of undiagnosed obstructive sleep apnea (OSA) should be considered when interpreting these results.