BMI and fertility: New insights into IVF outcomes in women with PCOS
image: Potential mechanisms linking obesity to adverse reproductive outcomes in infertile patients with PCOS.
Credit: Xiao-Lei Ji; Qing-Chen Cui; Lin-Zi Lei; Jian-Kang Zhang; You-Zhu Li.
For many women with polycystic ovary syndrome (PCOS), achieving pregnancy can be challenging. PCOS is one of the most common hormonal disorders affecting women of reproductive age and a leading cause of infertility related to irregular or absent ovulation.
A new review suggests that body mass index (BMI) may play an important role in how patients with PCOS respond to in vitro fertilization (IVF) treatment.
Published in Reproductive and Developmental Medicine, the review examined current evidence on the relationship between BMI and IVF outcomes in women with PCOS. Chinese researchers assessed how different BMI levels may affect fertility treatment, pregnancy outcomes, and potential underlying factors.
The relationship between BMI and IVF outcomes is complex. Some studies reported no significant differences in implantation, pregnancy, miscarriage, or live birth rates between patients with higher and normal BMI. However, other large studies and meta-analyses found that overweight and obesity were associated with poorer ovarian response, lower live birth rates, and increased miscarriage risk.
Higher BMI may affect several stages of IVF treatment. Excess body weight may reduce the ovaries’ response to stimulation, influence egg and embryo quality, and affect the ability of the uterine lining to support embryo implantation. Factors such as insulin resistance, increased androgen levels, and chronic low-grade inflammation may contribute to these effects.
Low BMI may also influence treatment outcomes. Some studies linked low BMI with lower pregnancy and live birth rates, increased miscarriage risk, and certain adverse newborn outcomes, although evidence remains inconsistent.
The authors emphasized that BMI should not be considered alone when planning fertility treatment. Individual factors, including metabolic health, body composition, and lifestyle, should also be taken into account. Lifestyle changes remain important components of weight management. For some patients, additional medical or surgical approaches may be considered as a second-line option.
The review also highlights the need for more personalized approaches to weight assessment in fertility care, which may support better reproductive outcomes for women with PCOS undergoing IVF. Future research should explore factors beyond BMI, such as fat distribution, waist-to-hip ratio, and metabolic markers, to better predict IVF outcomes.