The pattern of serum melatonin levels during ovarian stimulation for in vitro fertilization.

OBJECTIVE

To characterize the relationship between the pineal gland hormone, melatonin, and gonadal hormones.

METHODS

We studied the pattern of serum melatonin at the time of ovarian stimulation for in vitro fertilization. Blood samples were obtained every morning, from 20 healthy women during the in vitro fertilization cycle.

RESULTS

A progressive rise in serum estradiol and prolactin was noted in all IVF cycles, while serum melatonin levels remained unchanged throughout the cycles. In two of the subjects the circadian rhythm of serum melatonin was assessed at 4-hour intervals for 24 hours. In both subjects the melatonin rhythm was remarkably consistent in terms of phase, amplitude, and total melatonin secreted during the treatment cycles.

CONCLUSIONS

These results indicate that endogenous estradiol, progesterone, and prolactin do not affect the levels or circadian phase of melatonin secretion in humans.