During the recent decades with increasing the use of assisted reproductive techniques including IVF, IUI and ovulation induction, the rate of multiple pregnancies has been increased worldwide. More than 30% of ART pregnancies are twins or higher-order multiple gestations (triplets or greater) a frequency 15- to 20-fold greater than with spontaneous conceptions. Because of the high cost of treatment and the relatively low success rate of such treatments (which is improving every day), a decision is sometimes made to implant several fertilized eggs.Many studies indicate that multiple pregnancies have negative impact on families’ emotional wellbeing and are associated with social and financial burden on couples.From 1980s, multifetal pregnancy REDUCTION has been introduced as an efficacious method to reduce fetal number and improve the survival of remaining fetuses.Since most of the fetal loss subsequent to embryo REDUCTION occurs several weeks after the procedure, an inflammatory response to dead fetoplacental tissue with releasing of cytokines and stimulation of prostaglandins might leads to fetal loss, uterine contractions and preterm labour.In a large multicentre study, improved outcomes were observed by multifetal pregnancy REDUCTION done by expert hands in terms of fetal loss and early prematurity.The most important complication of high order multifetal pregnancies (more than two) is preterm delivery ranging from 32% to 86% in different studies. In a recent study in Royan Institute report that fetal REDUCTION of triplets to twins leads to 4% increase in miscarriage rate and couldn’t be demonstrated any correlation with the initial number of fetuses and other outcomes such as preterm birth, gestational age at delivery and birth weight of neonates. In this study the extreme prematurity was more common in non reduced group compared to reduced group. As a consequence, the mean gestational age at delivery for reduced group was significantly higher than expectantly managed group and the average gestational length was 4 weeks longer in the reduced group. Furthermore, in the current study, the mean birth weights of neonates were higher in the reduced group than control group and the percentage of low birth weight infants (<2500 g) was significantly higher in the expectantly managed group. As prematurity is the most important cause of neonatal and perinatal deaths and subsequent handicap infants, prolongation of gestational age at delivery due to fetal REDUCTION could less the rate of deaths and handicap among survivors. But as ultrasound equipment improved and doctors gained technical expertise, the procedure triggered fewer miscarriages.Genetic diagnosis before REDUCTION is becoming more common, safe in experienced hands.The ultimate goal in prevention is to significantly reduce the likelihood that any multifetal pregnancy will occur, including twins.REDUCTION is hardly the only area in which reproductive innovation has outpaced cultural consensus.The justification for eliminating some fetuses in a multiple pregnancy was always to increase a woman’s chance of bringing home a healthy baby, because medical risks rise with every fetus she carries. Not only does the danger to the mother increase with more fetuses, but also the risk of miscarriage, ending the lives of all of the fetuses increases. Ultimate decision of patients depends on: extent of their religious and antiabortion sentiments, whether they medical-scientific careers, how proactive the advice from physicians has been.