When you’re trying to get pregnant, it’s important to understand the basics about fertility, beyond the simple fact that you need an egg and a sperm, and they need to meet at the right time, for conception to occur. How long is a woman’s egg viable after ovulation? The fact is, this is normally only a matter of between 12 and 24 hours. Does this mean that you have just a one-day window each month to become pregnant? Happily, no. Mother nature has a few tricks up her sleeve to allow a longer fertility window of up to a week each month.

Read on to find out more about ovulation and how the fertility window works:

• What is ovulation?
• What happens to your egg after ovulation?
• How long does an egg live after ovulation?
• What can you do to improve your chances of conception?
• What can you do to keep eggs viable for longer?

What is ovulation?

The whole point of your menstrual cycle is the production of one, occasionally two, mature and viable eggs each month, and this is the basis of your fertility. Here’s a run-down of the cycle. It can broadly be divided into four phases: menstruation, the follicular phase, ovulation, and the luteal phase, although there is some overlap, as we shall see.

• Counting the first day of your period as day one, the first phase of menstruation, otherwise known as your period, starts and lasts for between three and seven days. During this time your uterus sheds its lining which consists of blood, mucus, and some cells from the uterus, and it flows out from your vagina.
• The follicular phase also starts on day one, and continues for 13 or 14 days, culminating (in a regular 28-day cycle) in ovulation. In this phase, prompted by the release of a hormone from the brain’s pituitary gland, follicles, each containing an immature egg, start to develop on the surface of the ovary. The uterus lining also starts to thicken.
• At ovulation, one of the developing follicles which has overtaken the others during the follicular phase, becoming the leading follicle, bursts and releases the mature egg. Once released, it survives in a viable state for 12 to 24 hours.
• In the luteal phase, the empty follicle, now a corpus luteum, releases progesterone and a small amount of estrogen, further thickening the uterus lining in preparation for pregnancy. If a fertilized egg implants, it continues to produce progesterone to support the uterus lining. If not, the corpus luteum is reabsorbed, levels of progesterone fall, and the uterus lining sheds in the start of the next period.

What happens to your egg after ovulation?

We have seen that how long an egg lives after ovulation are measured in hours rather than days, normally between 12 and 24 hours. It’s also clear that what happens to the egg after ovulation is entirely dependent on whether conception occurs. If the egg is fertilized by a sperm, this normally happens in the fallopian tube and the fertilized egg continues on its way down the tube to the uterus, there to implant in the uterus lining. If no sperm is present during the limited amount of time it remains viable, it simply disintegrates and is shed along with the uterus lining during your period.

What can you do to improve your chances of conception?

Luckily, even though your egg remains viable for such a short time after ovulation, sperm are rather more durable. Sperm can survive and remain capable of fertilizing an egg for up to five days inside your body. It follows that, rather than the short space of time allotted to the egg, your fertile window is in fact more like five or six days in any one month. So, if you have sex during the few days before you ovulate, or on the day itself, you still have a good chance of becoming pregnant. However, a successful attempt to conceive still depends on your knowing when, or roughly when, you are due to ovulate. This can be achieved in several ways:

• The simple diary method involves keeping a note of the dates when your period starts each month. From this, if your cycle is regular, you can calculate its length. Once you know the likely date of the start of your next period, you can work backwards and calculate your probable ovulation date by subtracting 14 days from this date.
• An ovulation predictor kit, available at pharmacies, works by measuring the increase in luteinizing hormone which occurs just before you ovulate. You need to take the test for a few consecutive days for the rise to be detectable. Once this happens, you are advised to have sex daily for the next few days.
• The cervical mucus method involves observing the quality of your vaginal discharge. When ovulation is due, it takes on a clear, thin and stringy consistency, something like egg white. The purpose of this is to help sperm swim towards the released egg, and it is the ideal time for intercourse.

What can you do to keep eggs viable for longer?

If you have a good diet, a healthy weight and exercise sensibly, and if you have regular periods, there’s a good chance that you are ovulating and will experience the monthly window of fertility that we have described. However, no matter how good your health or lifestyle, there is no known natural method of increasing the length of time that your eggs remain viable once you have ovulated. The only way that this can be achieved is with the help of the technique known as egg freezing.

The preservation of fertility does not extend the viable life of your eggs during the natural menstrual cycle, but is a way of extending your opportunity for fertility over a longer timescale if you think you may want to have children, but the time is not yet right. It involves hormonal treatment to encourage the development of several, rather than the usual one, eggs and then retrieving them in the same way as for the In Vitro Fertilization (IVF) technique. They are then frozen and stored so that you can decide on the right time.

In one sense, this changes the answer to the question of how long a woman’s egg remains viable. With the right techniques, the answer could be – as long as you want! Contact us at IVI to find out more.