The relationship between embryo quality and obesity in IVF patients: a single-center retrospective study

Purpose: The aim of this study is to retrospectively compare the relationship between female obesity and embryo quality and pregnancy outcome.Materials and methods: In this retrospective study, which received approval by the ethical committee, data of in vitro fertilization (IVF) patients (n:542) between January 2019 and August 2021 were examined. The patients were divided into four groups: Group 1, Body Mass Index (BMI) <18.50 kg/m2 (n:16); Group 2, BMI 18.50-24.99 kg/m2 (n:263); Group 3, BMI 25.00-29.99 kg/m2 (n:156); Group 4, BMI ≥30 kg/m2 (n:107). Demographic characteristics of patients, baseline hormone levels, treatment protocols employed, counts of collected oocytes, day of embryo transfer, transferred embryo quality, a positive pregnancy test, and live births were collected, and statistical analysis was performed.Results: There were no significant differences between the groups in terms of age, collected oocyte count, number of mature oocytes, maturation rate (p>0.05). Group 4 showed a statistically significant decrease in the number of 2PN (p=0.014) and fertilised oocyte count (p=0.006) compared to Group 2. When comparing pregnancy outcomes based on BMI groups, it was found that obesity did not significantly affect positive/negative pregnancy rates, live birth rates, miscarriage rates, biochemical pregnancy rates among the groups (p>0.05). Logistic regression analysis indicated a decrease in embryo quality with increasing age. Multiple regression analysis (MRA) results showed that a good quality of the transferred embryo had a positive impact on achieving a positive pregnancy outcome. The presence of pregnancy was negatively affected by increasing age. In Group 1 and Group 2, there were significantly more Day-5 transfers than in Group 4 (p=0.008).Conclusion: This study showed that obese patients had a lower rate of Day 5 embryos compared to non-obese patients. However, no difference was found between BMI and pregnancy rates. The development of good quality embryos had a favourable effect on pregnancy outcomes, whereas increasing age had a negative effect. The present data suggest that further studies evaluating the mechanism underlying the effect of obesity on embryo development are warranted.