Ovulation occurs when a mature egg is released from the ovarian follicles into the fallopian tube about 10–12 hours after the peak in LH surge. Most times only one of the 15–20 follicles that have been stimulated reaches full maturity, and just one egg is released. Ovulation only occurs in around 10% of cycles during the first two years following menarche, and by the age of 40–50 the number of ovarian follicles is depleted. Luteinising hormone initiates ovulation at around day 14 and stimulates the formation of the corpus luteum. In turn, and following further stimulation by luteinising hormone, the corpus luteum produces and releases estrogen, progesterone, relaxin (which relaxes the uterus by inhibiting contractions of the myometrium), and inhibin (which inhibits secretion of more luteinising hormone).