Rising multiple maternity rates and medical management of subfertility: better information is needed.

Multiple maternity rates rose rapidly from the mid-1970s onwards in many Western countries. This has major public heath implications, as multiple pregnancies can lead to many problems for the mothers and their children. Ovarian stimulation and assisted reproductive technology (ART) play a major role in these trends but there are few data about them. Consistently defined multiple maternity rates, including twin and triplet maternity rates are needed annually for each country in order to monitor time trends and make international comparisons. In order to assess the contribution of ovarian stimulation and ART to trends in multiple maternities and to monitor their impact on pregnancy outcome, fuller and more consistent data are needed. These could be collected from ART centres and other care providers, or through medical birth registries or national surveys.