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Ovulation and Your Fertile Window: When to Try for a Baby

How ovulation works, how long the fertile window lasts, and the signs and tools that can help you time sex.

Before you use this guide: This is general educational information, not an individual medical assessment. We do not identify a clinician reviewer on this page, so please confirm personal health decisions with your doctor, midwife or paediatrician.

You can only get pregnant on a few days each cycle. Understanding ovulation, when an ovary releases an egg, helps you make the most of those days without turning trying for a baby into a chore.

How the fertile window works

An egg survives for roughly 12 to 24 hours after it is released, while sperm can survive in the body for up to about five days. This means your fertile window is around six days long: the five days before ovulation and the day of ovulation itself. The two or three days just before ovulation are usually the most fertile.

Ovulation usually happens about two weeks before your next period starts. In a regular 28-day cycle that is often around day 14, but if your cycles are longer, shorter or irregular, the timing moves with them.

Signs that ovulation may be close

• Cervical mucus becomes clear, wet and stretchy, a little like raw egg white.
• Some women notice a mild, one-sided ache in the lower tummy around mid-cycle.
• Your sex drive may rise slightly.
• Resting body temperature rises a little after ovulation. This confirms ovulation has already happened, so it is more useful for learning your pattern than for timing sex.

Tools that can help

• Ovulation predictor kits are urine tests that detect the surge in luteinising hormone (LH) that comes shortly before ovulation. A positive result usually means ovulation is likely within the next day or two.
• Period and fertility tracking apps estimate your fertile days from past cycles. They are only as accurate as the information you enter, and they cannot confirm ovulation on their own.
• Writing down your cycle length for a few months shows you your own pattern.

Keep it simple

Many doctors advise having sex every two to three days throughout the month rather than trying to pinpoint one perfect day. This covers your fertile window without the stress of exact timing. More than eight in ten couples who have regular unprotected sex conceive within a year.

When to seek advice

Talk to your doctor if you have been trying for a year without success, or after about six months if you are 35 or older. See them sooner if your periods are very irregular or have stopped, if you have a known condition such as polycystic ovary syndrome (PCOS) or endometriosis, or if you have had pelvic infections or surgery. Fertility checks usually involve both partners, and asking for them is a sensible step, not a sign that something is wrong.

This content is for general information only and is not medical advice. Every pregnancy and every baby is different. Always talk to your doctor, midwife or paediatrician about your own situation, and seek urgent care if you are worried.