The basics · 4 min read
Fertility simply means the natural ability to conceive a child. It sounds straightforward — but it is shaped by age, biology, lifestyle and timing in ways that aren't always obvious. Here's a gentle introduction.
For most healthy couples under 35, around 84% will conceive within a year of regularly trying, and around 92% within two years, according to NICE guidance. That also means roughly 1 in 7 couples in the UK experience some difficulty conceiving — fertility challenges are far more common than most people realise.
Conception relies on several things lining up: a healthy egg, healthy sperm, open fallopian tubes, a receptive uterus, and the right hormonal timing. A difficulty in any one of these areas can affect your chances. The NHS notes that fertility issues affect both women and men roughly equally, which is why investigations look at both partners.
Women are born with all the eggs they will ever have. Both egg quantity and egg quality decline gradually from the late twenties and more steeply after 35. The Human Fertilisation and Embryology Authority (HFEA) publishes detailed UK data on how IVF success rates change with age — useful context whether or not treatment is on your mind.
Lifestyle won't override age, but it does matter. Not smoking, keeping alcohol modest, maintaining a healthy weight and managing long-term conditions all support fertility for both partners. For men, sperm production runs on a roughly 72–90 day cycle, so changes made today are reflected in results around three months later.
Understanding fertility early — in your twenties or early thirties — gives you the widest range of options later. Whether that's simply knowing where you stand, considering egg freezing in your twenties, or starting a conversation about treatment options, knowledge gives you choice rather than urgency.
