Ovulation and fertile window

This page is reference information compiled from the cited sources. It is not medical advice. For any decision about health, diagnosis or care, consult a qualified professional.

What it is

Ovulation is when a mature egg is released from the ovarian follicles into the pelvic cavity and enters the fallopian tube. This event occurs about 10–12 hours after the peak in the luteinizing hormone (LH) surge. It is the release of an oocyte from the ovary. Ovulation is part of the ovarian cycle, which consists of the follicular phase, ovulation, and the luteal phase. The process involves the dominant follicle, which is the one that reaches maturity and is called an antral follicle, releasing its egg.

Key facts

Ovulation occurs around day fourteen of the menstrual cycle. It is triggered about 10–12 hours after the increase in luteinizing hormone, known as the LH surge. Typically only one of the 15–20 stimulated follicles reaches full maturity and releases an egg. The oocyte lives for 24 hours or less without fertilization after ovulation. Peak levels of estrogen are reached at around day thirteen of the cycle and coincide with ovulation. The surge of FSH and LH usually occurs one to two days before ovulation and is responsible for stimulating the rupture of the antral follicle.

When to seek professional help

The source text describes situations where symptoms affect daily living. More severe symptoms that affect daily living are classed as premenstrual dysphoric disorder, and are experienced by 3–8% of women. The menstrual cycle can cause some women to experience premenstrual syndrome with symptoms that may include tender breasts and tiredness. During the first few days of menstruation some women experience period pain that can spread from the abdomen to the back and upper thighs.

Source: Menstrual cycle (CC BY-SA 4.0 (Wikipedia)), retrieved 2026-09-19.