Why age matters
Age is the biggest single factor affecting female fertility. The number of eggs falls over time, and so does the proportion that are chromosomally normal. That's why the chance of conceiving each month tends to fall, and the risk of miscarriage tends to rise, from the mid-thirties onwards.
Male age matters too, although the changes are more gradual. Sperm quality and DNA integrity can decline with age, so it's worth looking at both partners.
When to seek advice
If you're 35 or over and haven't conceived after six months of trying, it's generally sensible to get advice rather than waiting a full year. If you're over 40, or you have irregular cycles or a known health condition, it's worth doing so sooner.

