To compare the pregnancy outcomes of pregnancy outcomes after selective fetal reduction treatment in monochorionic, dichorionic, and trichorionic triplet pregnancies. We conducted a retrospective analysis of the clinical data of 118 pregnant women carrying triplets. All subjects underwent regular prenatal check-ups and were admitted for delivery at West China Second University Hospital, Sichuan University between January 1, 2012 and January 31, 2021. According to the chorionicity, the subjects were divided into a monochorionic group ( n=13), a dichorionic group ( n=44), and a trichorionic group ( n=61). Within each group, the subjects were further divided into two subgroups, a reduction group and an expectant treatment group, according to whether they underwent fetal reduction or not. The clinical data and pregnancy outcomes were compared between the subgroups within each group. In the monichorionic group, the reduction subgroup had a lower preterm birth rate and higher neonatal birth body mass than those of the expectant management subgroup, but the differences were not statistically significant. In the dichorionic and trichorionic groups, the rates of preterm delivery, neonatal hospitalization, and serious complications of the reduction subgroups were lower than those of the expectant subgroups ( P<0.05), while the neonatal birth body mass was higher in the reduction subgroups than that in the expectant subgroups ( P<0.05). In the dichorionic group, the incidence of intrahepatic cholestasis during pregnancy was lower in the reduction subgroup than that in the expectant treatment subgroup. In all 3 groups, there was no statistically significant difference between the subgroups in the incidence of gestational diabetes, hypertensive disorders of pregnancy, premature rupture of membranes, and postpartum hemorrhage. The survival curve analysis showed that women receiving fetal reduction during the first trimester had a lower risk of pregnancy loss and more significant prolonged of gestational age than those undergoing the procedure during the second trimester. Fetal reduction of triplets can significantly prolong the gestational age and improve the perinatal prognosis. In addition, selective reduction in the first trimester may lead to greater benefits than selective reduction in the second trimester does.