The role of mode of conception in the outcome of twin pregnancies.

Artificial reproductive techniques (ART) have become a routine and successful treatment of infertility. Twin pregnancies are more frequent after ART compared to spontaneous conception. Varying findings have been reported for the obstetric and perinatal outcome of ART twin pregnancies as compared to spontaneously conceived twin pregnancies. To evaluate the specific risks of twin pregnancies achieved through ART, literature has been reviewed for obstetric and perinatal risks and differences between artificially and spontaneously conceived twin pregnancies. Eleven studies have been involved in this review. Three of the studies were matched and eight were non-matched studies. Results of analysed studies differed widely. Twin pregnancies resulting from ART showed an increased rate of Caesarean section and tend toward higher risk for preterm birth and low birthweight compared to spontaneously conceived twin pregnancies. Various conditions can influence twin pregnancies outcome after ART. In in-vitro fertilization programs twin pregnancies should be avoided and physicians have to inform patients of the specific risks when transferring more than one embryo.