Ovulation: when it happens, the signs, and what helps

Key takeaways

• Ovulation usually happens about two weeks before your next period, not always on day 14.
• A surge of luteinizing hormone (LH) triggers it, and home ovulation tests look for that surge.
• The fertile window is about six days: the five days before ovulation and ovulation day.
• Body temperature rises only after ovulation, so it confirms ovulation rather than predicting it.
• A cycle tracking app is not birth control unless it is certified for that use.

Ovulation at a glance

When does ovulation happen?

Ovulation usually happens about two weeks before your next period. In a 28-day cycle that is around day 14, but the day can move from cycle to cycle and from woman to woman.¹

One study that measured hormones every day found that only about 30% of women had their fertile window fully within days 10 to 17, the days often quoted in guidelines. Most reached it earlier and some much later. The authors noted that timing can be highly unpredictable, even when cycles are usually regular.²

This is why counting days on a calendar is only a rough guide. Illness, stress and travel can sometimes shift when you ovulate, too.

What are the signs of ovulation?

The most common signs are changes in cervical mucus, a positive ovulation test, a small rise in body temperature after ovulation and, for some women, a one-sided ache in the lower tummy. Not everyone notices every sign.

• Cervical mucus. As estrogen rises, discharge often becomes wetter, clearer and more slippery, a bit like raw egg white.³
• LH surge. A sharp rise in luteinizing hormone triggers ovulation. Home ovulation tests detect it in urine, and ovulation usually follows within about one to two days of a positive test.³
• Basal body temperature. Your resting temperature rises slightly after ovulation, by roughly 0.3 to 0.5 °C (about 0.5 to 1 °F), and stays higher until your period. It confirms ovulation after the fact. It cannot tell you in advance.³
• Mittelschmerz. This German word means "middle pain". Some women feel a dull ache or sharp twinges on one side of the lower tummy, lasting from a few minutes to a day or two. A little spotting or extra discharge can happen too. A warm bath or a simple painkiller may help.¹

How long is the fertile window?

About six days: the five days before ovulation and the day of ovulation itself. In a well-known study of 221 women trying to conceive, pregnancy only happened when sex took place within this six-day window.⁴

Sperm can survive for several days inside the body, while the egg lives for only a day or so after it is released.³ That is why the days before ovulation matter most.

Because ovulation can move, the window moves with it. If you are trying to get pregnant, ovulation tests and mucus changes may help you spot it. If you are trying not to, please read the birth control section below.

How might I feel around ovulation?

Many women feel more energetic, confident and social around ovulation, and some notice a higher sex drive. Others feel little change, and a few feel uncomfortable because of ovulation pain.

Estrogen peaks just before ovulation, which may be part of why some women feel this way.³ These are patterns, not promises. Your own experience is what counts, and it can change from cycle to cycle.

Should I train differently around ovulation?

Most women can train as normal, and many feel strong at this point in their cycle. Research on whether ovulation changes injury risk is mixed, so a good warm-up matters more than skipping sessions.

Some studies find that knee ligaments become slightly looser at certain points in the cycle. But a 2023 systematic review concluded that it is inconclusive whether any cycle phase raises the risk of a knee (ACL) injury, and it rated the quality of the evidence as low to very low.⁵

A thorough warm-up, gradual increases in load and good technique help at any time of the month. If your sport involves jumping, landing or sudden changes of direction, injury prevention exercises are worth doing all cycle long.

What should I eat around ovulation?

There is no special ovulation diet. Plenty of vegetables, fiber, protein and water will cover you, and you may find your appetite lower now than in the week before your period.

Lighter, fresher meals are fine as long as you still eat enough, especially on training days. If you are trying to get pregnant, ask your doctor or pharmacist about taking folic acid.

How can I plan my week around ovulation?

If you tend to feel confident and social at ovulation, it can be a good time for things that need you to be seen and heard. Research on planning by phase is limited, so let how you actually feel lead.

• Work: the pitch, the negotiation, the presentation or the hard conversation.
• People: dates, parties, dinners and time with friends.

Regime Longevity predicts your phases from the periods you log and turns them into a daily plan for food, training, sleep and work. Those predictions are estimates. They show when ovulation is likely, never when you are safe from pregnancy.

Can a cycle tracking app be used as birth control?

Not unless the app is specifically certified as a method of contraception. Most cycle and wellness apps, including Regime Longevity, only estimate your phases and should never be used to decide when you can have unprotected sex.

Even fertility awareness methods taught properly depend on careful daily tracking of several signs. The NHS says that with typical use they are only about 76% effective, which means around 24 in 100 women get pregnant in a year. It also says that none of the apps or devices for tracking fertile days are officially recommended by the NHS.⁶

If you need contraception, talk to a doctor, nurse or sexual health clinic about the options that suit you.

When should I see a doctor about ovulation?

See a doctor if ovulation pain is severe, does not ease with painkillers or keeps coming back, or if you have one-sided pain and could be pregnant. Also get advice if your periods are very irregular or stop, or if getting pregnant is taking longer than you hoped.

One-sided pain in early pregnancy needs checking because it can be a sign of an ectopic pregnancy. Pain that keeps coming back can sometimes be linked to conditions such as endometriosis or an ovarian cyst, so it is worth getting looked at.¹ A doctor can also check whether you are ovulating if you are trying for a baby.

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