IL-18 and IL-18 binding protein concentrations in serum and ovarian follicular fluid do not affect in vitro fertilization outcomes in obese, overweight, and non-obese patients

Obesity causes the specific upregulation of proinflammatory cytokines and chemokines. One of these cytokines, IL-18, has a well-known association with obesity. Our aim in this study was to test the effect of serum and intrafollicular IL-18 and IL-18 binding protein (BP) levels on in vitro fertilization outcomes in obese, overweight, and non-obese patients. Serum and pooled follicular fluid levels of IL-18, IL-18BP, and the IL-18/IL-18BP ratios were evaluated in 21 non-obese (body mass index [BMI] <25), 37 overweight (25 ≤ BMI <30), and 24 obese (BMI ≥ 30) patients undergoing in vitro fertilization. IL-18 and IL-18BP levels in serum and follicular fluid did not change with obesity. There was no correlation among serum intrafollicular IL-18, IL-18BP levels, and the number of oocytes retrieved and transferred, embryo grades or pregnancy ratios. The levels of serum and intrafollicular IL-18, IL-18BP, and the IL-18/IL-18BP ratios do not seem to be related to in vitro fertilization outcomes in obese, overweight, and non-obese patients.