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Identifying your fertile window

11 September 2020

The fertile window is the time of the month when pregnancy is possible. Identifying your fertile window and having intercourse during this time increases your chances of pregnancy. In this article we tell you how to identify your fertile window.

Fertile Window: the best days to conceive

Even though we are taught that pregnancy can happen easily, any time, this is actually not true. Conception is only possible for about 6 days a month – your fertile window. These 6 days include the day of ovulation and up to 5 days before ovulation. This is because the egg survives around 24 hours after ovulation, and the sperm survives up to 5 days in the female reproductive system.

How to identify the fertile window?

There are several ways to identify those days of the month when pregnancy is possible. However, some methods are more reliable than others. In general, these methods are measuring hormonal changes that happen around ovulation or measuring physical signs that happen as a consequence of those hormonal changes.

  1. Cervical mucus: during your fertile window, cervical mucus becomes very wet, stretchy and resembles a raw egg white. This is important because it allows sperm to swim easily to find the egg. When making note of what your cervical mucus looks like every day, you will notice these changes around your fertile days. This method has 48-76% accuracy.
  2. Basal body temperature: basal temperature changes throughout the cycle depending on your progesterone levels. This method implies measuring your temperature every morning, at the same time, before any activity. Before ovulation, temperature reaches its lowest point (nadir), and after ovulation, it increases, as the corpus luteum starts producing progesterone. Because we cannot identify the lowest point, before we notice the increase, this method only confirms ovulation after it has happened, and the fertile window is over. For this reason, basal body temperature it’s not a good indicator of fertile window, with only 22% accuracy. It is, however, an indicator that ovulation has happened and there is no more chance of conception in that cycle.
  3. LH Surge: is the most accurate method to identify your fertile days, at 97% reliability. LH is produced by the pituitary gland in the brain and is responsible for the later stages of egg maturation and for triggering ovulation. LH levels start increasing 35-44h before ovulation, giving you an indication that you are in your fertile window and still have a few days to time intercourse and get pregnant!

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