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Your Fertile Window

You are actually fertile for less time than you might think. In every menstrual cycle you can only get pregnant when your body is ready: the cycle is all about preparing your body for pregnancy, and only when it’s made those preparations can you conceive successfully.

In the first part of your menstrual cycle your body is preparing eggs to be ovulated. They are stored in the ovaries, in small, fluid filled sacs called ‘follicles’. At the beginning of your cycle, when you begin your period (which is essentially clearing away the previous cycle’s now unnecessary preparations for pregnancy), around ten immature (or ‘primaeval’) follicles are selected and begin to develop. Over the course of around two weeks they grow towards maturity, until the healthiest follicle dominates and the others are reabsorbed by the body. At the end of this ‘follicular phase’ the egg is ovulated.

From the time it’s ovulated, that egg is viable for twenty four hours (or less! Diet, health conditions and simply poor luck can all lead to an egg that’s not as long lived). Your fertile window is anchored by when you ovulate: you need to overlay the lifespan of sperm after ejaculation with the date of ovulation and that 24 hours afterwards. This tells you when your fertile window is: the time span in which sperm and eggs could meet while they’re both viable, and sperm could fertilise egg.

Sperm can survive as long as five days after sex, which gives you a six day fertile window – the five days before ovulation and the day after. Finding out when it is in advance could make all the difference in your attempts to get pregnant!

Many of the most well-known and popular fertility tracking methods don’t give you access to this full six days of high fertility. Ovulation predictor kits are easy to use and widely available but will only tell you when you have ovulated, giving you a day or less of fertile time. BBT tracking can alert you that your body is preparing to ovulate but this is, at most, only another 24 hours of notice.

OvuSense works by tracking minute changes to your core temperature through a specially designed sensor. These are fed directly to our algorithm which turns them into a map of your progesterone levels, which it can use to predict when you will ovulate.

Unlike other methods of ovulation prediction, ours begins to provide useful notifications after only two days of using the sensor. You don’t have to wait a full cycle to apply what you’ve learned: you can start planning for pregnancy right away!

Learn more about fertility and pregnancy here