A common question among many women trying to conceive is about the fertile window. Can pregnancy happen on different days in different cycles or does it only happen during a certain period? The answer to these questions is as complex as the human body itself. Many women may struggle when trying to get pregnant because they can’t distinguish their fertile period.

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All the changes that can happen from cycle to cycle and from body to body can be confusing for someone trying to conceive, but we can say that the ovulation period is never the same for everyone. There is only one similarity in cycles: there are 7 days of a fertile window during which eggs can be fertilized at any time. It all depends on how long it takes for the egg to mature enough to be released. What may change, then, is when the ovulation period happens in each cycle and for each woman, though not how many days it lasts, but when it will actually happen. So let’s understand this better:

An irregular cycle, for example, can vary in days because the time when ovulation occurs is never the same as the previous cycle. Normally, what varies in a cycle is the follicular phase, not the ovulatory phase and also the luteal phase.

That’s why it’s important to keep an eye on the signs your body gives when you’re approaching your fertile period. Some women may have a longer follicular phase (when the egg is developing) than in their previous cycle, and shorter than in the next. In theory, you should subtract 14 days from the total length of your cycle to get the correct follicular phase length:

A 37-day cycle would have on average a 23-day follicular phase – 37-14= 23
A 21-day cycle would have on average a 7-day follicular phase – 21-14= 7
A 28-day cycle would have on average a 14-day follicular phase – 28-14 = 14

In irregular cycles, the follicular phase can fluctuate a lot and that’s why it gets complicated to get pregnant by using calendar apps to track your ovulation. The best thing for those whose fertile period keeps changing is to look for alternatives such as getting to know your body, using ovulation tests, basal temperature and the Billings method.

The ovulation period of regular cycles, or cycles with little variation, is easier to identify because it does not change much within the cycle and works well with charts, calendars, and applications. The reason behind all these changes is certainly hormonal. The time it takes for FSH, estrogen and LH to be produced and the signal the brain receives from the ovaries to release certain essential hormones during the ovulation period. A body can have constant hormonal changes, so for anyone wanting to get pregnant, the ideal is to see a doctor when there are delays to check your hormonal condition.

Is It Possible to Get Pregnant Outside the Fertile Window?

No! A woman can get pregnant outside the day that would normally be her fertile period, but she only becomes fertile during ovulation. What happens is that the fertile window shifts dates and can make the cycle longer or shorter.

The ovulation period can come earlier or later. You can have very long cycles, up to 70 days, and a very late ovulation, or the opposite: the woman may have short cycles due to early ovulation. As stated above, the days before ovulation vary from woman to woman and can change from cycle to cycle. Ideally, for both regular and irregular women, you should check ovulation based on your own body signals to avoid missing ovulation. Charts and apps help a lot but can also cause you to miss your fertile days. Keep an eye on the signs your body gives you.

Some posts are interesting if you want to find your exact fertile period:

When does ovulation occur?
How to calculate the exact day of ovulation

Photo: Mixi Lorenzo