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What is the fertile window?

If you’re trying to conceive, you may be aware of the fertile window - but what is it and why is it so important? In this article, we take a closer look at this period of time during your menstrual cycle and how understanding it better could help you start a family.

What does ‘fertile’ mean?

The term ‘fertile’ relates to the ability to conceive or have children. Women are fertile over a number of days during their menstrual cycle. This is known as the fertile window or the pregnancy window. Meanwhile, male fertility doesn’t change in the same way as female fertility does.

When is the fertile window?

A woman’s fertile window depends on the length of her menstrual cycle, and this can vary considerably among women. The fertile window is the period of time in which having unprotected sex could result in pregnancy. It also includes the ovulation window.

Ovulation is when an egg is released from one of the ovaries, and it is critical in order to conceive. If you want to get pregnant, it can help to know when ovulation happens - especially since this window of opportunity to conceive is fairly small.

Put simply, ovulation typically occurs around 14 days before your period starts, and you are at your most fertile in the days leading up to it. So, in an average menstrual cycle of 28 days, ovulation would occur around day 14, with the most fertile days being days 12, 13 and 14. Pregnancy is possible if you have intercourse during the five days leading up to ovulation, or on the day of ovulation itself. This is due to the fact that sperm can live in fertile cervical mucus for up to this length of time, but you could still be fertile in the days following too. It’s also important to remember that the date of ovulation can vary with each cycle.

To work out when you are ovulating, there are a number of things you can do, and you may find using a combination of these methods works for you. For example, you can track your menstrual cycle, taking into consideration the length of the cycle to predict when ovulation might occur. You may want to keep track of this in a diary, or there are apps you can download to help too, such as Flo, Natural Cycles and Clue.

There are some physical signs that may indicate ovulation. For instance, you may notice that your cervical mucus becomes wetter, clear and more slippery during ovulation. You may also detect a small rise in your basal body temperature after ovulation takes place. This can be checked with a thermometer. Some women also experience breast tenderness, bloating and mild tummy pain during ovulation.

You could even use an ovulation predictor kit. Since hormone levels increase around the time of ovulation, these kits are designed to detect this by measuring the level of hormones in your pee and they can be an effective, straightforward way of monitoring ovulation.

Predicting ovulation to work out your fertile window can be tricky - even more so if you have irregular periods, as this can make tracking your cycle and pinpointing ovulation a difficult task. If you want to optimise your fertility and further support ovulation to maximise your chances of conceiving, you could try using a fertility supplement for women, or your doctor may be able to provide you with further help and advice.

How long is the fertile window?

The fertile window is normally around six days long. This period of time reflects the lifespan of the egg, which is 24 hours, and the lifespan of the sperm, which is up to five days, as the sperm can live in the female reproductive system for this length of time before an egg is even released.

While sperm is resilient, egg cells are not, and they can deteriorate quickly after ovulation occurs. In fact, egg cells lose their quality as each hour passes, meaning that the chances of conception significantly decreases after this 24-hour period.

How often should I have sex during the fertile window?

The day prior to ovulation and the day of ovulation itself are usually a woman’s two most fertile days. This means your chances of conceiving is significantly increased if you have sex in the days leading up to this time. Ideally, you should try to have unprotected sex every two to three days around the time that you are ovulating. Over 80% of couples where the woman is under 40 years old conceive within a year of having regular, unprotected intercourse.

Can I get pregnant 2 days before the fertile window?

Generally speaking, you have a much lower chance of getting pregnant if you have sex two days before your fertile window. In fact, if you were to have sex six or more days before your fertile window, your chances of getting pregnant are slim to none - although it’s not impossible, especially if you have inaccurately predicted your ovulation date, or you ovulate earlier in your cycle.

Determining your fertile window and paying attention to your menstrual cycle can help provide important information about your body, particularly when you are trying to conceive.