What Is Ovulation and How Can You Recognise It?

Ovulation is the moment when a mature egg is released from the ovary and travels into the fallopian tube. It’s the point in your cycle that opens the possibility of conception. The egg survives for around 12–24 hours after release. If it meets a sperm during that time, fertilisation can occur.

But this doesn’t mean only intercourse on the day of ovulation can lead to pregnancy. Sperm can survive in a woman’s body for an average of 2–3 days, and under ideal conditions (with the right cervical mucus) for up to 5 days. This was confirmed by the landmark Wilcox study published in the New England Journal of Medicine, which showed that conception is possible even from intercourse that took place 5 days before ovulation. That’s why your “fertile window” isn’t just one day, but roughly 6 days: 5 days before ovulation + the day of ovulation itself.

Source: Wilcox AJ, et al. “Timing of sexual intercourse in relation to ovulation.” N Engl J Med. 1995;333(23):1517–1521.

A common myth says ovulation always falls on day 14 of your cycle. That’s an oversimplification which can be misleading.

Ovulation typically occurs 12–16 days BEFORE your next period (not after your previous one). That’s an important distinction.

If your cycle is 28 days, ovulation probably falls around day 14. But if your cycle is 32 days, ovulation could be around day 18. And if your cycle is irregular, the timing may shift from month to month.

Source: Wilcox AJ, et al. “The timing of the ‘fertile window’ in the menstrual cycle.” BMJ. 2000;321(7271):1259–1262.

Your body gives several signals that ovulation is approaching or has just occurred. Here are the key ones:

1. Cervical mucus

This is the most accessible and completely free method. In the days before ovulation, your cervical mucus changes:

• After your period: little to no mucus, or dry
• A few days before ovulation: mucus becomes moist, white, creamy
• Just before ovulation: mucus is clear, slippery and stretchy (like egg white)
• On the day of ovulation: mucus is at its most fertile abundant, clear, very slippery and highly stretchy (you can stretch it between your fingers for several centimetres without it breaking). It resembles raw egg white. This is the mucus that creates the environment where sperm can survive the longest and most easily reach the egg.
• After ovulation: under the influence of progesterone, mucus quickly thickens, becomes white or creamy and loses its stretchiness, forming a natural barrier to sperm

“Egg white” mucus is the signal that you’re in your fertile window.

Source: Bigelow JL, et al. “Mucus observations in the fertile window: a better predictor of conception than timing of intercourse.” Hum Reprod. 2004;19(4):889–892.

2. Basal body temperature (BBT)

Basal body temperature is your body’s temperature right after waking, before any activity. After ovulation, BBT rises by approximately 0.2–0.5°C and stays elevated until your next period.

Important: the temperature rise confirms that ovulation HAS already happened. It doesn’t predict it in advance. That’s why BBT works best combined with mucus observation.

To track BBT:

• Measure every morning at the same time, before getting out of bed
• Use a thermometer accurate to 0.01°C
• Record your results (in the app or on paper)

Source: Barron ML, Fehring RJ. “Basal body temperature assessment: is it useful to couples seeking pregnancy?” MCN Am J Matern Child Nurs. 2005;30(5):290–296.

3. Ovulation tests (LH strips)

Ovulation tests detect the surge in luteinising hormone (LH) in your urine. The LH surge typically occurs 24–36 hours before ovulation. A positive test means ovulation will likely happen within the next 1–2 days.

How to use them:

• Start testing a few days before your expected ovulation
• Test daily, ideally between 10am and 8pm
• Avoid drinking large amounts of fluid for 2 hours before testing

You can buy ovulation tests at pharmacies, supermarkets or online. Cheap test strips work just as well as expensive digital ones.

4. Ovulation pain (mittelschmerz)

Some women feel a mild ache or twinge on one side of their lower abdomen around ovulation. This is called “mittelschmerz” (German for “middle pain”). Not every woman experiences it and it’s not a reliable method on its own, but it can serve as an additional clue.

5. Other signs

It’s also worth paying attention to:

• Increased libido around ovulation
• Light spotting
• Breast tenderness
• A sense of the cervix feeling “open” (for those more experienced with self-examination)

Don’t rely solely on calendar apps. Most cycle tracking apps predict ovulation based on algorithms and average dates. This can be inaccurate, particularly if you have irregular cycles. An app is a helpful tool, but it doesn’t replace observing your own body.

Source: Duane M, et al. “Fertility awareness-based methods for women’s health and family planning.” Front Med. 2022;9:858977.

Don’t stress about it. Stress affects the hypothalamic-pituitary-ovarian axis and can delay ovulation. Easier said than done, I know. But obsessively monitoring ovulation can paradoxically make conceiving harder.

More than you might think! Proper nutrition affects:

• Cycle regularity  calorie deficits and restrictive diets can disrupt ovulation
• Egg quality antioxidants, omega-3 and coenzyme Q10 support oocyte quality
• Hormone levels  insulin resistance (often linked to PCOS) can disrupt ovulation
• Cervical mucus  hydration and adequate fat intake affect its quality

The Mediterranean diet, rich in vegetables, fruit, fish, olive oil and whole grains, has shown positive effects on fertility in research studies.

Source: Karayiannis D, et al. “Adherence to the Mediterranean diet and IVF success rate among non-obese women attempting fertility.” Hum Reprod. 2018;33(3):494–502.

1. Start observing your cervical mucus  simply pay attention. You don’t need to be an expert straight away.
2. Buy ovulation test strips  the cheapest ones from the pharmacy will do for starters.
3. Note your cycle length from the first day of your period to the next first day. Gather data from your last 3 cycles if you can remember.

“Health is the greatest human value”

Oksana Rozponczyk Clinical Dietitian | AnaskoMed Clinic

References:

1. Wilcox AJ, et al. Timing of sexual intercourse in relation to ovulation. N Engl J Med. 1995;333(23):1517–1521.
2. Wilcox AJ, et al. The timing of the “fertile window” in the menstrual cycle. BMJ. 2000;321(7271):1259–1262.
3. Bigelow JL, et al. Mucus observations in the fertile window: a better predictor of conception than timing of intercourse. Hum Reprod. 2004;19(4):889–892.
4. Barron ML, Fehring RJ. Basal body temperature assessment: is it useful to couples seeking pregnancy? MCN Am J Matern Child Nurs. 2005;30(5):290–296.
5. Duane M, et al. Fertility awareness-based methods for women’s health and family planning. Front Med. 2022;9:858977.
6. Karayiannis D, et al. Adherence to the Mediterranean diet and IVF success rate among non-obese women attempting fertility. Hum Reprod. 2018;33(3):494–502.
7. Reed BG, Carr BR. “The Normal Menstrual Cycle and the Control of Ovulation.” In: Endotext. 2018.
8. Colombo B, Masarotto G. Daily fecundability: first results from a new data base. Demogr Res. 2000;3(5).