When you’re trying to get pregnant, there is no more important even in your calendar than when you ovulate. Ovulation is the key event in your fertility cycle that defines when you can actually get pregnant each month – in order for sex to actually result in pregnancy you need to be trying at a time when sperm can encounter a fertile egg. Sperm can remain active in the body for four to five days after ejaculation, while an egg has at most a 24 hour life span before it becomes infertile.

Ovulation is the process at fulcrum of your cycle, when an egg is released from the ovaries into your fallopian tubes. Knowing when that happens allows you to focus your attempts to conceive on that vital few days leading up to it, and giving the best chance to get pregnant when you want to.

Challenges

Predicting ovulation isn’t always easy. If you’re lucky enough to have a very regular cycle then you simply counting off the days and marking them on an ovulation chart can give you an accurate measure of when you’re due to ovulate. With a regular cycle, simply knowing the date your last period began lets you slot everything else into place, but not all women are so lucky.

Irregular cycles can be an occasional issue, caused by illness or by medication for example, they can be a recurrent problem or they can be the reality you live with your whole life. For some women, an irregular ovulation cycle is caused by Polycystic Ovary Syndrome, otherwise known as PCOS. This is a hormone driven issue: too much insulin leads in turn to too much androgen, which delays the maturation of eggs in your ovaries. This can lead to ovulation happening at unpredictable intervals, or even being skipped altogether, with a period happening despite no egg being released into your system.

In cases like this it’s even more important to start predicting when you ovulate: fewer ovulations mean fewer chance to get pregnant so each one is more precious.

Basal Body Temperature

One of the most accurate means of predicting when you’re going to ovulate is to chart your basal body temperature. This is the low minimum temperature your body drops to when you’re asleep. Variations of a tenth of a degree at this low level reveal the deep processes governing your body, and if chart it every day, using an accurate thermometer you can use those patterns to spot when you ovulate. Even better, modern apps and computer programmes can interpret the data for you, giving you a prediction of the best time for you to get pregnant.