Ovulation typically occurs near the midpoint of the menstrual cycle, around day 14 in a 28-day cycle. More precisely, it happens about 12 to 16 days before the start of the next period. However, this can vary between days 11 and 21 depending on the individual and the length of her cycle. The process is triggered by a surge in luteinizing hormone (LH), and ovulation usually occurs 24 to 36 hours after this LH surge. The egg is released from the ovary and can be fertilized for up to 24 hours after ovulation. The fertile window includes the five days before ovulation and the day of ovulation itself, with the highest likelihood of conception in the three days leading up to and including ovulation. In summary:

• Ovulation occurs about midway in the menstrual cycle.
• Around day 14 of a 28-day cycle (12-16 days before the next period).
• Triggered by an LH surge.
• Fertile phase includes days before and the day of ovulation.
• The egg survives about 24 hours after release.

This timing can vary among women and from cycle to cycle in the same woman.