Ovulation

Spermatozoa arriving at an egg.
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What is ovulation?

Ovulation is when one or more eggs are released from one of your ovaries. This happens toward the end of the time you’re fertile between periods.
Getting to know how to recognize when you are ovulating is one of the most powerful ways women have of gaining control over their own fertility, and yet it’s often something that seems mysterious and difficult to grasp. Here we share the secrets of how ovulation works, and how you can learn to recognize your fertile periods by reading the clues your body give you.
Each month, between 15 and 20 eggs mature inside your ovaries. The ripest egg is released and swept into one of your fallopian tubes, which then connect your ovaries to your uterus (womb).

Your ovaries do not necessarily take turns releasing an egg. It happens quite randomly.

How does ovulation influence when I can get pregnant?

To become pregnant naturally, one of your eggs and your partner’s sperm have to meet in your fallopian tube. Your egg survives no more than 24 hours after you’ve ovulated. So the meeting of egg and sperm has to occur within this time.

However, sperm can survive for up to seven days. They’ll happily live in your vagina, uterus or fallopian tubes for this length of time (NCCWCH 2004: 27).

This means that you don’t have to time sex to the exact moment you ovulate to get pregnant. You actually have a fertile window of about six days.

This window includes the five days before and the day of ovulation itself (Lynch et al 2006). So, if you have sex at some time during your fertile window, your freshly ovulated egg could meet live, healthy sperm and be fertilized.

How can I tell when I’m most fertile?

The simplest way to work out your most fertile time is to note down the length of your menstrual cycle. Then look out for signs of hormonal and physical changes in your body.

You’ll start to notice signs that you’re fertile about five days before you ovulate. Ovulation usually occurs between 12 and 14 days before your period starts (Fehring et al 2006). This is an average, so it could be a couple of days earlier or later.

For example, say you have a regular 28-day menstrual cycle. Count the first day of your period as day one. Your fertile window is likely to be around days 12 to 17.

However, a lot of women have an irregular cycle. If your cycle is irregular, ovulation may occur a week earlier or later from one month to the next (Fehring et al 2006).

Working out your fertile window using your cycle dates alone is an inexact science. This is why learning to spot your body’s fertile signs can help. These include:

Changes in cervical mucus

Cervical mucus is the discharge that you see in your underwear or on toilet paper when you pee.

Changes in your cervical mucus can signal when you are fertile (Bigelow et al 2004, Alliende et al 2005, Scarpa et al 2005, Campbell and Rockett 2006). After your period has finished, your cervical mucus gradually increases in amount and changes in texture.

This change reflects the rising levels of the hormone estrogen in your body. It also shows you are close to ovulating (Bigelow et al 2004, Campbell and Rockett 2006).

You are most fertile when your mucus becomes clear, slippery and stretchy. It’s a bit like raw egg white. This fertile mucus speeds the sperm on its way up through your uterus. It nourishes and protects the sperm as it travels towards your fallopian tubes to meet your egg.

See our photo gallery to check what cervical mucus looks like.

An ache in your belly

About a fifth of women can actually feel something happening in their ovaries around ovulation. This can range from mild achiness to twinges of pain (Vorvick and Storck 2009). Some women feel ovulation as one-sided backache or a tender area. The condition, called mittelschmerz, may last anywhere from a few minutes to a few days.

If you notice these sensations at roughly the same time each month, check your cervical mucus. Ovulatory pain can be a useful guide to when you’re fertile.

Feeling sexy

Feeling sexy, flirty and more sociable may all be signs that you’re at your most fertile (Haselton and Gangestad 2006).

You may notice a peak in sexual desire at this time (Pillsworth et al 2004, Gangestad and Thornhill 2008: 992). You may find your partner becomes a little more attentive as a result. There’s medical evidence for this (Gangestad and Thornhill 2008: 995)!

You may not be aware of it, but you may be showing other signs that you are at your most fertile. Think back over your cycle and you may remember the following happening:

  • Looking and feeling great: you’re likely to feel more physically attractive as you near ovulation (Gangestad and Thornhill 2008: 996). You may be more attractive to others, too (Haselton et al 2007, Durante et al 2008).
  • Scent of a woman: you smell good at this time. Your body odour is more pleasant and sexy to men around the time you’re fertile (Gangestad and Thornhill 2008: 996). You may think that nobody knows you’re ovulating-and consciously, they don’t-but those natural scents may quietly give the game away.

Try our ovulation calculator to help you work out when your fertile window is likely to be.
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How can I increase my chances of getting pregnant?

Try to have sex every two to three days. Then sperm with good motility will be in the right place whenever you ovulate. Regular sex throughout your cycle gives you the best chance of conceiving (NCCWCH 2004: 27).

Making love when your cervical mucus is wet, slippery and most receptive to sperm will also increase your chances of conception (Bigelow et al 2004; Scarpa et al 2005). And you’ll be happy to know that the odds are with you.

In normally fertile couples, there is between a 20 per cent and a 25 per cent chance of getting pregnant each cycle (Wood 1994, Leridon and Slama 2008).

Eighty-four per cent of women who have regular sex without using contraceptives will get pregnant within a year (NCCWCH 2004: 26). Ninety-two per cent of couples conceive within two years.

Find out which are the best sexual positions for baby-making.

References


CKS. 2008. Menopause. Clinical Knowledge Summaries, Clinical topic. www.cks.nhs.uk [Accessed October 2010]

Fehring RJ, Schneider M, Raviele K. 2006. Variability in the phases of the menstrual cycle. J Obstet Gynecol Neonatal Nurs 35(3):376-84

Levin RJ. 2002. The physiology of sexual arousal in the human female: a recreational and procreational synthesis. Arch Sex Behav 31(5):405-11

Lui PD. 2007. Biology of the male reproductive system. The Merck Manuals www.merck.com [Accessed October 2010]

NCCWCH. 2004. Fertility: assessment and treatment for people with fertility problems. National Collaborating Centre for Women’s and Children’s Health, Clinical Guideline. London: RCOG Press. www.rcog.org.uk [pdf file, accessed October 2010]

Rebar RW. 2008. Sperm disorders. The Merck Manuals www.merck.com [Accessed October 2010]

Katie MacGuire
Katie MacGuire is an award-winning journalist and entrepreneur. She created an extensive library of evidence-based maternal health articles for BabyCenter Canada.

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