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What Day of your Cycle do you Ovulate?

Finding out when you ovulate is important when you’re trying to get pregnant. If you want to boost your chance of conceiving as soon as possible, you need to track when you ovulate so you can make sure you’re trying at the best time for your fertility.

A woman’s fertility waxes and wanes through the month, and if you want to find your fertile days, which are also known as your ‘fertile window’, then you need to start by tracking your ovulation. When you ovulate, the egg released from your ovaries is fertile for up to 24 hours. This means you have a single date from the point at which the egg is ovulated for that egg to encounter sperm.

That doesn’t mean you have to have sex in that 24 hours. The lifespan of sperm is significantly longer than the egg, and sperm cells can survive in the body after ejaculation for around five or six days. This means that if you can identify when you’re going to ovulate, you can count back that five days to find the start of your fertile window: the time when the average lifespan of both sperm and eggs overlap.

It would be an easy thing to find if everyone ovulated at exactly the same point in their cycle, but unfortunately the human body can vary in its patterns and cycles. Some people have a very regular menstrual cycle of 21 days, while others can be as long as 35 days. Even when two women have the same length of cycle, they might ovulate at different times. Other women have different lengths of cycle every month, making it particularly hard to anticipate when ovulation’s going to happen.

Ovulation happens at the end of the ‘follicular phase’ – the first phase of your menstrual cycle that begins on the first day of your period. It’s called this because in this stage your ovaries begin to prepare eggs to be ovulated in small sacs called follicles. The follicular phase itself can be of different lengths – on average it’s 16 days but it could be anywhere between 11 and 27 days in length.

The best way to find the day when you ovulate in your cycle is to track your Basal Body Temperature. The changes at this low level can show that your body is preparing to ovulate. OvuSense can help with this: our system uses a specialised sensor to take your temperature automatically, right through the night. It then feeds out to an app that can give you a personalised prediction of the next time you’ll be at your most fertile.