How to track ovulation and find your fertile window

Pregnancy is possible on only a few days of each cycle, and they are not the same days for everyone. Recognising them needs no special equipment, just a little attention over two or three cycles. Here is how the cycle works, which signs to look for and when to see a doctor.

Cycle basics

Day 1 of the cycle is the first day of proper bleeding, not spotting. The cycle ends the day before the next period starts. A normal cycle lasts 21 to 35 days; 28 is only an average.

Ovulation is the release of a mature egg from the ovary. It happens about 14 days before the next period, not on day 14 of the cycle. The second half of the cycle, from ovulation to the period, is fairly constant at 12 to 16 days in most women; it is the first half that varies. So in a 30-day cycle ovulation is usually around day 16, and in a 24-day cycle around day 10. If your cycle length varies, the day of ovulation moves with it.

The fertile window and how to use it

The egg survives for about 12 to 24 hours after release, while sperm can live in the woman's body for up to five days. The fertile window is therefore about six days long: the five days before ovulation and the day itself. The chance of conception is highest in the two or three days just before ovulation and falls sharply the day after. Because the window opens before the egg is released, the aim is to notice ovulation approaching, not to confirm it afterwards.

Sex every one to two days through the fertile window gives the best chance; every two to three days across the whole cycle works nearly as well and takes the pressure off. Saving up for several days does not improve sperm quality, and long gaps can reduce it. Avoid lubricants unless they are labelled sperm-friendly, as many ordinary ones slow sperm down.

Signs your body gives

• Cervical mucus. In the days after a period there is usually little discharge. As ovulation approaches it becomes more plentiful, then clear, slippery and stretchy, like raw egg white. This is the most useful everyday sign because it appears before ovulation. Afterwards the mucus turns thicker and cloudy, or disappears.
• Basal body temperature. Your resting temperature rises by about 0.2–0.5 °C after ovulation and stays higher until the period. Measure it every morning before getting out of bed, at the same time and with the same thermometer, and write it down. The rise confirms ovulation only after the fact, so it is most useful over several cycles to learn your pattern rather than to time a single month.
• Mild one-sided pain. Some women feel a dull ache or a brief twinge low on one side around ovulation. Not everyone has it, and alone it is not reliable.
• Other changes. Breast tenderness, higher libido or light mid-cycle spotting are common but too vague to time intercourse by.

Ovulation tests and apps

Home ovulation tests detect the surge of luteinising hormone (LH) in urine that comes about 24 to 36 hours before the egg is released. Start testing a few days before you expect to ovulate, based on your shortest recent cycle, at the same time each day; early afternoon often works better than first morning urine. A positive result means the next one to two days are your most fertile. They are less reliable with PCOS or very irregular cycles, because LH can be raised at other times too.

Cycle-tracking apps are a good diary and remind you when to start testing, but their predicted ovulation day is a calculation from past cycles, not a measurement. Treat it as a hint and check it against mucus or a test.

Irregular cycles and when to see a doctor

A few days of variation is normal, and travel, illness or a stressful month can delay ovulation. Cycles consistently shorter than 21 days or longer than 35, or that swing unpredictably by more than a week, deserve a closer look. Common causes include marked weight gain or loss, very intensive exercise, thyroid problems, raised prolactin and polycystic ovary syndrome (PCOS), which often comes with acne, excess hair growth or long gaps between periods. Most are treatable, and treatment often restores regular ovulation.

Make an appointment at your polyclinic or ayollar maslahatxonasi if:

• your cycles are irregular, very long or absent;
• your periods are very heavy or painful, or sex is painful;
• temperature charts or tests suggest you are not ovulating;
• there is no pregnancy after 12 months of regular unprotected sex when you are under 35, or after 6 months when you are 35 or older.

Your partner should be checked too, since sperm problems contribute in a large share of cases.

A few myths

• Position and time of day do not matter. Sperm reach the cervix within minutes in any position, and lying still afterwards makes no measurable difference.
• Timing cannot choose the baby's sex. The idea that sex close to ovulation gives boys and earlier sex gives girls has been studied and does not hold up.
• You can conceive during a period. It is uncommon, but possible with short cycles or long bleeding, because sperm live for several days.

This article is general information, not medical advice. Talk to your doctor about your own situation.