Quadruplet pregnancy outcomes with and without fetal reduction: Danish national cohort study 2008‐2018 and comparison with dichorionic twins

To perform a nationwide study of quadrichorionic quadruplet pregnancies and to compare the pregnancy outcomes in those undertaking fetal reduction with non-reduced quadruplets and dichorionic diamniotic twin pregnancies from the same period.A Danish national register-based study was performed from 2008 to 2018 using data from the national Danish Fetal Medicine Database, which included all quadrichorionic quadruplets and all non-reduced dichorionic diamniotic twin pregnancies. The primary outcome measures were gestational age at delivery, adverse pregnancy outcome with pregnancy loss and intrauterine fetal death of one or more fetuses, the number of liveborn children, preterm delivery before 28, 32, and 37 weeks, and birth weight. Data on pregnancy complications and baseline characteristics were also included. A systematic literature search was performed to describe and compare results with our Danish study.A total of 33 quadrichorionic quadriamniotic quadruplet pregnancies and 9,563 dichorionic diamniotic twin pregnancies were included in the study, with 3 (9.1%) non-reduced, 28 quadruplets (84.3%) reduced to a twin pregnancy, and < 3 (6.1%) reduced to singletons. Overall, rates of adverse pregnancy outcomes were highest in non-reduced quadruplets (66.7%), 50% in quadruplets reduced to singletons, and 10.7% in quadruplets reduced to twins. All preterm delivery rates before 37 weeks were improved in quadruplets reduced to twins compared to non-reduced quadruplets. Quadruplets reduced to twins did not achieve equivalent pregnancy outcomes to dichorionic diamniotic twins.This national study of quadrichorionic quadruplets has shown multifetal pregnancy reduction to improve pregnancy outcomes, including decreased rate of preterm delivery and higher number of liveborn children. This article is protected by copyright. All rights reserved.