Obstetric outcome of twin pregnancies after in-vitro fertilization: a matched control study in four Dutch University hospitals

In singleton pregnancies after in-vitro fertilization (IVF), increased rate s of obstetric and perinatal complications have been reported. Studies that compared IVF twin pregnancies with spontaneously conceived twins have yiel ded conflicting results. We compared 96 IVF twin pregnancies to 96 controls after elaborate matching. The design of our study precluded matching by zy gosity. The monozygosity rate was higher in the control group and this impl ies that beforehand the risk for a less favourable outcome in the control g roup was higher than in the IVF group. However, the average birthweight of the IVF children was less than that of children in the control group (P = 0 .04). This was not due to more intrauterine growth retardation in the IVF g roup. The mean gestational age at birth was 5 days shorter in IVF than cont rol pregnancies, and although this difference was not significant it might explain the lower birthweight in the IVF group. The discordance rate in the IVF group was significantly increased. We found no difference in perinatal mortality and morbidity. We conclude that this study provides further evid ence for a different outcome of IVF twin pregnancies in comparison with spo ntaneously conceived twin pregnancies.