According to the WHO, fertility problems can come from either partner or both. That is why guidelines suggest that both partners are checked when it takes longer.
Everyday habits
Guidelines mention habits that support general and sperm health: not smoking, keeping alcohol low, regular movement and a healthy weight. Some medicines and supplements, such as anabolic steroids, can affect sperm, so it is worth asking a doctor or pharmacist.
Sperm take around three months to develop, so changes in habits take time to show.
The first check
A semen analysis is the usual first test. It is simple and done in a lab. If a result is unusual, it is often repeated after about three months. A doctor explains what the result means.