Melatonin concentration in follicular fluid is correlated with antral follicle count (AFC) and in vitro fertilization (IVF) outcomes in women undergoing assisted reproductive technology (ART) procedures.

The aim of the present study was to evaluate the possible relationship between melatonin levels in the follicular fluid (FF) and in vitro fertilization (IVF) outcomes in women undergoing assisted reproductive treatment. Sixty-three females (20 to 40 years old) scheduled for IVF were divided into three groups based on their antral follicle count (AFC). We determined FF melatonin concentrations in group A (AFC≦6, n = 21), group B (7≦AFC≦14, n = 22), group C (AFC≧15, n = 20) on oocyte retrieval day. Patients in group C had significantly higher melatonin levels as compared to patients in groups A and B (p < .001). Melatonin levels of the patients were significantly positively correlated with antral follicle count (AFC, p < .001), serum anti-Müllerian hormone(AMH) levels (p =.001), serum estradiol (E2 ) levels on human chorionic gonadotropin (HCG) administration day (p = .001), total follicle-stimulating hormone (FSH) dose (p = .002), starting FSH dose (p = .035), number of retrieved oocytes (p < .001), total fertilized oocytes (p < .001), normally fertilized oocytes (p < .001), cleaved oocytes (p < .001), number of high-quality day 3 embryos (p = .004), blastocysts obtained (p = .007) and total embryos obtained (day3 embryos + day5/6 blastocysts) (p = .005). The levels were significantly negatively correlated with age (p < .001), basal serum FSH levels (p = .003), serum FSH (p = .001) and serum luteinizing hormone (LH) levels (p = .003) on HCG administration day. This is the first demonstration of a significant positive correlation of melatonin concentrations with AFC in patients undergoing IVF. We propose that FF melatonin levels may influence the IVF outcomes.