In theory, during the average woman’s menstrual cycle there are six days when sex can result in pregnancy. This conception risk period, also called ‘fertile window’ is the five days before egg release (ovulation), plus the day of egg release.
You are at risk of conception if you have unprotected sex in the 5 days before ovulation because sperm can live for about 5 days, and can be waiting in the fallopian tubes, ready to fertilise your egg. Unless fertilised, an egg only lives for 24 hours.
The highest risk of pregnancy is when ovulation happens shortly after unprotected sex
Sperm viability declines in the days after sex. This means that the risk of conception is highest when ovulation happens during the first three days following unprotected sex.
When is this conception risk period?
You have no way of knowing when your fertile window is – and it can be at a different time every month.This means that you are at risk of pregnancy almost throughout the whole of your menstrual cycle.
- You might not ovulate on the same day of your cycle from one month to another
- Women with a regular cycle can be in their fertile window any time from day 6 to day 21
- If the cycle is not regular, the fertile window may be even later in the cycle
- It is difficult to predict when your fertile window may be, and it can be a different time every month