If you are young, healthy and have a good chance of conceiving after IVF, you are at greatest risk of a multiple pregnancy.
A new baby brings its own joys as well as its own stresses. Many people find that having two or more babies can prove to be an unexpectedly difficult experience.
Up to half of all multiple pregnancies result from fertility treatment; around a quarter of all twins and most triplets are born following IVF treatment.
Compared with singletons, twins are 4 times more likely to die in pregnancy, 7 times more likely to die shortly after birth and 6 times more likely to have cerebral palsy.