The most important outcome of infertility treatment is a birth of a healthy baby. In many countries, in-vitro fertilisation treatments carry a high risk of twin pregnancy, which brings a higher risk to the mother and child than singleton pregnancies. Preterm delivery and low birth weight are the main factors accounting for the excess in neonatal morbidity. The use of elective single embryo transfer combined with cryopreservation can minimise the twin rate. Recent studies have shown that repeat single-embryo transfer can produce more live births per oocyte retrieval than double-embryo transfer. Ovulation-induction treatment protocols can also be improved and optimised. Correct counselling is important, as many infertile couples may desire twin pregnancies. Good counselling should include realistic information on the risks of twin gestation and also on later burdens with a multiple birth.