The existence of a 5-day fertile period doesn’t mean that there’s no truth to the idea that every day carries some risk. It all depends on your very own unique cycle, how your body does things and how aware you are of what is happening on any given day.
“There are days during your cycle when you are fertile and days when you are not. The difficulty is knowing which days those are. Our hormones and therefore our menstrual cycle can be affected by a number of factors making our fertility unpredictable,” says Deborah Evans, a pharmacist with over 35 years of experience.*
*Deborah Evans does not endorse any products or brands.
“It’s not just a case of when the egg is released at ovulation but how long the sperm are viable and present to cause fertilisation; this can span a number of days,” says Deborah. “Knowing when we are fertile assumes that we’re like clockwork; some people are, but a lot of people are not.”
Not every cycle is 28 days long. Even if yours is, the different phases of your cycle (before, during, and after ovulation) can vary in length. It’s really hard to pinpoint the exact time of ovulation and it could vary no matter how regularly your period shows up. There are many reasons this could happen – including changes to your sleep pattern, stress, travel or diet – and sometimes it can just fluctuate for no identifiable reason at all.
Some people don’t find out just how irregular their 28-day cycle can be until they do get pregnant and their first ultrasound scan shows that they are a week (or maybe even more) behind what they had expected based on their last menstrual period. This could mean that they got pregnant when they didn’t think they were ovulating.