Fertility, explained simply

Usually if you are under 35 and have been trying for 12 months, or 35 and over and trying for 6 months. Go sooner if periods are very irregular or absent, if there is a known condition such as PCOS or endometriosis, or after more than one miscarriage.

Both partners matter: in a large share of couples, a male factor plays a part.

Doctors often start with hormone blood tests for the woman (such as AMH and thyroid), an ultrasound scan, and a semen analysis for the man. Your doctor decides what you need.

Intrauterine insemination: prepared sperm is placed directly in the uterus around the time of ovulation. It is simple, quick and often one of the first treatments tried.

In vitro fertilisation: eggs are collected, joined with sperm in a lab, and an embryo is placed in the uterus a few days later. Extra good embryos can be frozen for later.

A form of IVF where a single sperm is injected into each egg in the lab. It is often used when sperm count or movement is low.

Anti-Müllerian hormone gives a sense of a woman's egg reserve. It does not measure egg quality, and a low AMH does not mean pregnancy is impossible. Your doctor reads it together with age and scans.

Polycystic ovary syndrome can make ovulation irregular. Many women with PCOS conceive, sometimes with lifestyle changes and simple treatment to help ovulation.

Eggs are collected and frozen to use later. It is usually most effective at a younger age; a specialist can explain what suits you.