This study was conducted for determining pregnancy outcome after selective fetal reduction in twin pregnancies based on the gestational age at the time of the procedure in a referral academic center between 2017 and 2021. This retrospective cohort study included all women with twin pregnancies who were diagnosed with a genetic or structural anomaly of one fetus or a desire to reduce the number of fetuses in order to reduce pregnancy complications visited in the period of 2017-2021. Reduction was performed due to an abdominal approach at 11 to 23 weeks of pregnancy. Maternal and pregnancy information were recorded. A total of 159 cases of twin dichorionic pregnancies were included. The highest frequency of reduction was performed at the gestational age of 18-20 weeks, and the most common cause of reduction was major structural anomalies in the fetus. The results showed the average gestational age (GA) at the time of delivery to be 37.6 weeks, the average birth weight of 2,999 grams, the incidence of miscarriage (loss before 22 weeks) to be 9.4% and a rate of preterm birth (delivery before 37weeks) of 33.3%. There is not a statistically significant relationship between the gestational age at the time of reduction and preterm birth, the birth weight, the incidence of RDS and the incidence of SGA. Fetal reduction of twins to singleton pregnancy is associated with lower risk of preterm birth (delivery before37 weeks reduction of twins to singleton pregnancy is associated with lower risk of preterm birth (delivery before37 weeks). It causes an increase in birth weight and perinatal outcome in remaining co-twin so we recommend fetal reduction after counselling with patients for their unique situation to improve pregnancy outcome.