Ovulation and fertile window: how to spot them

Ovulation doesn’t always happen on day 14. Here’s how to estimate it, the signs that can announce it, and the limits of the calculation.

When does ovulation happen?

Ovulation happens about 14 days before your next period. The phase after ovulation (the luteal phase) is fairly steady, lasting between 12 and 16 days, while the first part of the cycle varies more. With a 28-day cycle, ovulation falls around day 14; with a 32-day cycle, closer to day 18.

The fertile window

The egg lives for about 24 hours, but sperm can survive for up to 5 days. So the fertile window covers about 6 days: the 5 days before ovulation and the day of ovulation.

Signs that can announce it

• Cervical mucus becomes more abundant, clear and stretchy, like raw egg white.
• Your temperature on waking rises slightly (by 0.2 to 0.5 °C) after ovulation and stays high until your period.
• Some women feel a slight pain on one side of the lower belly or tender breasts.
• Ovulation tests sold in pharmacies detect the rise of a hormone (LH) one to two days before.

The limits of the calculation

The calendar calculation is still an estimate: stress, illness or an irregular cycle can shift ovulation. It is not a reliable method of contraception. To avoid pregnancy, talk to a health professional about contraception.

Ragnagna is not a medical device and does not replace advice from a health professional. If in doubt, talk to your doctor, midwife or gynaecologist.