When the time comes to start a family, your fertility suddenly becomes important. Too many people approach it as a binary question, asking simply ‘am I fertile?’. Yes is a good answer to get, but even within that your fertility changes across the course of time (over the weeks of your menstrual cycle, as well as the years of your life), so you need to know when you’re most fertile so you can concentrate your attempts to conceive then, and give yourself the best chance at getting pregnant quickly. If you’ve been having trouble conceiving, it’s well worth taking a close look at the fertility before you decide it’s not a possibility for you.

The Fertility Cycle

Your cycle (the fertility cycle or menstrual cycle) is the process of changes your body goes through each month (they typically last for between 28 and 35 days) to prepare to make a baby. In the initial stages you experience your period. This is your body clearing out the endometrial lining laid down in the previous cycle to nurture a fertilised egg: if an egg doesn’t get fertilised the lining is expelled. It is, of course, far from pleasant – it causes pain, the degree of which varies from woman to woman, but even at it’s lightest it’s a serious discomfort, and the hormones that control the process also affect your mood.

While this is happening, your body is also beginning to mature eggs in your ovaries. Each month up to twenty eggs in total begin to grow to full maturity in small, fluid filled sacs called follicles. That’s why this phase of your cycle is called the Follicular phase. The healthiest egg is released into the fallopian tube while the others are broken down and absorbed by the body.

Next is the Luteal phase: while the egg moves slowly towards the uterus, the uterus itself is building up a thick, endometrial lining. We know what happens if the egg isn’t fertilised – if it is, it eventually makes it’s way to the uterus to embed in the lining and develop into a foetus.

That egg is only fertile for a maximum of 24 hours after it’s released from the ovary, so to get pregnant, you need to know when you ovulate. If you don’t have intercourse in the fertile window (when the lifespan of sperm and eggs overlap) then your chances of pregnancy plunge.

Fortunately a modern fertility device makes it easy by taking accurate basal body temperature readings and turning those into a prediction of when you’ll next ovulate, and when you should try to conceive to give yourself the best chance of success and starting the next stage of your journey.