Glandular fever is an infectious illness that's caused by the herpes family of viruses. Lots of people have already had the virus by the time they're an adult, but symptoms may have been so mild you didn't realize. Once you've had glandular fever, your body makes antibodies against it, and it's extremely rare to get it again.

It's hard to catch glandular fever because it is spread in saliva through intimate contact such as kissing. It's most common in teenagers and young adults.

Because it is difficult to catch and more common in young people, glandular fever doesn't usually pose a risk to pregnant women. If you do catch it while pregnant, there is no evidence that it harms the unborn baby.

In severe cases of glandular fever, complications such as jaundice, hepatitis and brain inflammation can occur. However, this is very rare, and most people recover within a few weeks.