Perinatal outcomes of monochorionic monoamniotic twin pregnancies

To describe the risk of early and late fetal loss of a cohort of monochorionic monoamniotic (MCMA) twin pregnancies; secondary objectives are to describe perinatal outcomes of these pregnancies and to identify which obstetric variables mostly influence the incidence of neonatal adverse outcome.

Retrospective cohort study including MCMA twin pregnancies followed up at the Twin Pregnancy Care Unit of Sant'Anna Hospital in Turin (Italy) between 2005 and 2024. Chorionicity and amnionicity were diagnosed in the first trimester.

A total number of 53 MCMA twin pregnancies have been included in the study, of which 42 progressed beyond 24 weeks of gestation. The rate of fetal loss before 24 weeks of GA was 19.8 %, after 24 weeks this rate lowered to 3.6 %; the incidence of overall intrauterine losses was 23.6 %; 80.5 % of liveborn twins were female. Around one fourth of the newborn babies had an adverse outcome, the likelihood of which was significantly influenced by gestational age at birth, birthweight and presence of malformations. The incidence of congenital malformations in our sample was 13.4 %.

Most fetal losses occur before 24 weeks of gestation and the rate of fetal demise after this cutoff is quite low. It could be worth to postpone elective delivery to 34 weeks of gestational age or beyond, in order to reduce perinatal complications associated to premature birth.