Background Monochorionic (MC) pregnancies are routinely delivered electively at various late preterm gestations with the intention of avoiding stillbirth. The aim of this study is to evaluate the prospective risk of late stillbirth in a large regional cohort and systematic review.

Methods A retrospective study of all twin births of known chorionicity from a regional cohort of 9 hospitals (STORK collaborative) taken over a 10 year period matched to a mandatory national register of stillbirth (CMACE). The data of the current study was included in a systematic review of selected studies of stillbirth in routinely managed twin pregnancies.

Results A total of 3005 twin pregnancies delivered after 26 weeks' gestation in the STORK collaborative, and this was combined with data from 8 studies selected from the systematic review. The prospective risk of stillbirth in MC twins did not change significantly between 26+ weeks (3.6 per 1000 fetuses) and 36+ weeks (5.2 per 1000 fetuses, OR 1.85, 95% 0.3-13.2). The equivalent figures for DC twins were 0.8 per 1000 fetuses and 1.7 per 1000 fetuses, respectively (OR 3.4, 95% 0.9-13.2).

Conclusion The risk of stillbirth in MC twins does not appear to increase significantly near term. This observation may be due to a policy of routine surveillance and elective delivery from 36 weeks, the data does not support a policy of elective birth before 36 weeks' gestation in MC pregnancies.