EUROCAT study: The Risk of Congenital Anomalies in Multiple Births: a European Registry Based Study

Objectivesa) To assess the public health consequences of the rise in the rate of multiplebirths in Europe in terms of the associated risk of congenital anomalies: This willinclude: Assessment of the risk associated with singleton, twin and higher ordermultiple births for all CAs Determination of the prevalence of CAs which are specific to orembryologically influenced by twinning, including conjoined twins. Exploration of the evidence for the reported reduction in the prevalence ofchromosomal abnormalities, particularly Down s syndrome, in MBs. Examining the complex relationship between controlled ovarian stimulation(COS), assisted reproductive therapies (ART), multiple births, maternal ageand congenital abnormality.b) To describe the excess perinatal mortality due to congenital abnormality amongmultiple births in Europe and explore possible interpretations. This will include: Determining the perinatal mortality rates when a CA has been diagnosed inMB and singleton births and assessing whether any excess is explained byprematurity. Determining the prevalence of antenatal diagnosis of CA and itsconsequences, including selective termination of pregnancy and fetocide.c) To determine levels of concordance in twins. This will include concordance forthe same and for different anomalies.