[Multiples births: a continuing problem with assisted reproductive techniques].

Assisted reproductive techniques (ART) such as in vitro fertilisation (IVF), ovulation induction and superovulation followed by insemination have caused a sharp increase in multiple birth prevalence rates. The perinatal morbidity of multiple birth infants is high because of the high incidence of premature birth. The social and psychological problems of multiple birth families are also considerable. In 1990 high-order multiple births were mainly the result of IVF. Although the number of IVF treatments has increased more than the number of other ART treatments, nowadays high-order multiple births are predominantly caused by superovulation. Since 1990 the number of high-order multiple births has stabilised, but the recent sharp increase in ART twins results in a further rise in births of severely preterm ART infants. More restraint should be practised in superovulation treatments to bring down the number of (high-order) multiple births.