BACKGROUND Reproductive endocrinologists recommend selective multifetal pregnancy reduction (MFPR) to save at least one or two babies, because triplet pregnancy is known to increase the risk of miscarriage and preterm delivery. However, recently improved obstetric and neonatal care may affect pregnancy outcomes differently in triplet pregnancies, which could alter practice. We compared the maternal, perinatal, and long-term outcomes of triplet pregnancies managed expectantly with those of pregnancies reduced to twins. METHODS In this retrospective cohort study, we reviewed the clinical records of 552 trichorionic triplet pregnancies for obstetric, perinatal, and neurodevelopmental outcomes, which consisted of the expectant management (EM) group (n = 225) and MFPR group (n = 327), in Seoul National University Hospital and CHA Bundang Medical Center from January 2006 to December 2018. Neuromotor development was evaluated using the Korean-Ages and Stages Questionnaire, Bayley-III tests, and/or Gross Motor Function Measure. The two groups were compared for the following outcomes: (1) nonviable pregnancy loss before 23 weeks, (2) preterm birth before 32 weeks of gestation, (3) fetal and neonatal survival and (4) long-term neurodevelopmental outcomes. RESULTS There were no differences in maternal age, body mass index, nulliparity or previous preterm birth between the two groups. The risk of nonviable pregnancy loss was lower in the EM group than that in the MFPR group (2 [0.9%] vs 21 [6.4%], p = 0.001). The risk of preterm delivery before 34 weeks of gestation was lower in the MFPR group (adjusted odds ratios [aOR] = 0.47, 95% confidence interval [CI] 0.30-0.73, p = 0.001). The survival rate of neonates until discharge (644 [95.4%] vs 572 [87.5], p < 0.001) and the rate of pregnancies with at least one survivor (220 [97.8%] vs 301 [92.0], p = 0.002) were higher in the EM group than those in the MFPR group. In the MFPR group, the risk of developmental delay (aOR = 2.89, 95% CI 1.38-6.02, p = 0.005) was higher. CONCLUSIONS In trichorionic triplet pregnancies, the possibility of EM to improve survival and reduce the risk of developmental delay has been shown.