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Abstract Study question Is the probability of pregnancy different in women with and without dyslipidaemia undergoing in vitro fertilization (IVF)? Summary answer Women with dyslipidaemia demonstrate lower probability of achieving pregnancy compared to those without dyslipidaemia when undergoing IVF. What is known already Dyslipidaemia, including high concentrations of total cholesterol (TC) or low-density lipoprotein cholesterol (LDL-C) or triglycerides (TG), as well as low levels of high-density lipoprotein cholesterol (HDL-C) may affect fertility. Although the exact pathogenetic mechanisms have not been fully elucidated, dyslipidaemia-induced endothelial dysfunction may be identified. However, its specific impact on IVF outcomes remains inadequately studied. Study design, size, duration This systematic review and meta-analysis included cohort studies which evaluated the impact of dyslipidaemia on IVF outcomes. A comprehensive literature search of PubMed, Scopus and Google Scholar was conducted until January 2024. The primary outcome was live birth rates, while secondary outcomes included clinical pregnancy, cumulative live birth and miscarriage rates. Participants/materials, setting, methods Data from identified studies were independently extracted by two reviewers, including demographic, methodological and clinical information. Study quality was assessed using the Newcastle-Ottawa Scale. Statistical heterogeneity was evaluated using the I² statistic, and meta-analyses were conducted using random- or fixed-effects models, depending on the presence of significant heterogeneity. Results were expressed as relative risks (RR) or weighted mean differences (WMD) with 95% confidence intervals (CIs) and were analysed using an intention-to-treat principle. Main results and the role of chance Six retrospective studies (n = 11,685) published between 2018 and 2024 with moderate-to-low risk of bias were analysed. Sample size ranged from 127 to 3,372 patients. • Clinical pregnancy rates were lower in patients with dyslipidaemia compared to those without (RR 0.85, 95% CI 0.74–0.99; random effects model; I² 73.4%; five studies, 5,477 patients). • Dyslipidaemia was associated with higher miscarriage rate (RR 1.24, 95% CI 1.01–1.53; fixed effects model, I²: 0%; four studies, 5,019 patients) compared with normal lipid profile. • Patients with dyslipidaemia had lower live birth rates compared to those without (RR 0.82, 95% CI 0.68–0.99; random effects model; I² 89.4%; three studies, 4,972 patients). • No differences were noted in cumulative live birth rates between the two groups (RR 0.98, 95% CI 0.94–1.02; fixed effects model, I² 0%; two studies, 5,834 patients). Limitations, reasons for caution This analysis included a limited number of retrospective studies with moderate-to-low risk of bias due to methodological limitations. Considerable heterogeneity in terms of the population studied, criteria for dyslipidaemia definition and embryo transfer types necessitates cautious interpretation of findings. Wider implications of the findings This systematic review and meta-analysis is the first performed so far on this topic, showing decreased pregnancy outcomes in women with dyslipidaemia compared to those without. This underscores the importance of lipid profile screening before infertility treatment and necessitates prompt lifestyle intervention to reduce this effect. Trial registration number No