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Are You Fertile After Your Period?

Predicting when you’re going to be fertile isn’t always easy, but it’s very important when you’re trying to get pregnant. If you know when your fertile days will be, you have a better chance of getting pregnant, because you can plan to try to conceive when you’re more likely to succeed. If you don’t know when you’re fertile, you could miss chances and end up waiting longer.

It’s important to understand your fertile days (or ‘fertile window’) relative to your period – it’s the most visible sign of what’s happening in your reproductive system, so it’s very useful as a ‘landmark’ to navigate your fertility with.

What is your Fertile Window?

The days you are looking for, your fertile window, is the time when you have the best chance of getting pregnant each month. You find it by overlaying the average lifespan of sperm after ejaculation onto the date you ovulate, and the 24-hour maximum lifespan of the egg. This gives you a six-day period when the average sperm survives long enough to reach the egg while it’s still viable and potentially fertilise it.

It’s clear that the key event you need to identify and place relative to your period is ovulation: this gives you the information you need to plot out your fertile window.

When Do You Ovulate?

Ovulation happens at roughly the midpoint of your cycle: for roughly two weeks before you ovulate your body is maturing eggs in the ovaries. Around ten in each cycle start to grow towards maturity in small sacs called follicles (giving this part of your cycle the name ‘the follicular phase’). One eventually dominates while the others are reabsorbed.

After ovulation, your body shifts into the luteal phase, building up the lining in your uterus so it can support a fertilised egg. This phase is also often around two weeks long. It’s important to note, however, that even for women with very regular cycles, these two phases aren’t always entirely equal in length. If your cycle is 28 days long each time, you will ovulate, on average, on day 14. But you may not fit that average. If you have a longer follicular phase, you could ovulate on day 15 or 16, so unless you confirm when you ovulate you could miss some of your fertile window, and deprive yourself of opportunities to conceive.


Fortunately, this is where OvuSense can help. Our solution tracks your core temperature, which can tell you how much progesterone you are producing. Our clinically tested algorithm can turn this into detail fertility tracking, telling you where you are your menstrual cycle, when you ovulate and therefore when you will be fertile.

Learn more about fertility and pregnancy here