To work out the best time to fall pregnant, one needs to know how the menstrual cycle works. The monthly cycle is measured from the first day of the last menstrual period (LMP) until the first day of the next period, on average this cycle takes 28-32 days.³

Based on a 28-day cycle, and counting from the first day of the LMP, the date of ovulation can be anywhere between day 11-21.⁴ This is when females are the most fertile, and there is an increase in cervical mucus, which is the perfect medium as it helps to protect and nourish the sperm as it proceeds towards the egg.⁵ The egg only lives for a short time after leaving the ovary (12-48 hours), but sperm can survive between 3-5 days in the reproductive system.⁴

Millions of sperm are ejaculated during sexual intercourse, but only a few thousand reach the Fallopian tubes.⁶

However, there needs to be at least one healthy vigorous sperm already waiting in a Fallopian tube when the egg is released during ovulation.⁶

The best chance of conception occurring is when intercourse takes place any time from 5 days before ovulation. There is a 33% chance of falling pregnant if intercourse takes place on the day of ovulation.⁷