Many factors govern fertility, an important one being age. Womxn are born with all the egg-containing follicles in their ovaries that they will ever have.
Every month after your first period, until menopause, a small pool of eggs are chosen from this reserve to undergo maturation, but only 1 egg will ovulate. The remaining eggs degenerate, which is why the egg count keeps reducing. The better quality eggs are selected for maturation first, and as a result, the egg quality also decreases with age.
It’s not like fertility suddenly decides to take the plunge overnight on your 35th birthday. Fertility for womxn peaks in your 20s, and starts to decline gradually thereafter. It takes a steep decline in the mid-30s, almost coming to a standstill around the mid-40s as you approach menopause.
In the absence of physical barriers to conception such as blocked fallopian tubes, other influences on fertility or male factor infertility, to conceive on your own, you need to have enough good quality eggs. Age, lifestyle, environment, genetics and your health greatly influence the quantity and quality of the eggs. The chance of naturally conceiving each cycle declines from about 25% in the 20s to about 5% in the 40s.
After 35, the chances of pregnancy-related complications, miscarriage and genetic anomalies in the baby also increases. It’s important to remember that it is possible to have a lower than expected egg quantity before your 30s; this condition is called premature ovarian insufficiency.
Awareness about your fertility is essential to make informed choices about your reproductive health and future.
*The graph is only a visual representation and is not to scale.
References: NHS UK and ASRM.