Prevalence, antenatal management and perinatal outcome of monochorionic monoamniotic twin pregnancy: a collaborative multicenter study in England, 2000-2013

Ultrasound Obstet Gynecol. 2019 Feb;53(2):184-192. doi: 10.1002/uog.19114. Epub 2018 Dec 30.


Objectives: To determine the prevalence of monochorionic monoamniotic (MCMA) twin pregnancy and to describe perinatal outcome and clinical management of these pregnancies.

Methods: In this multicenter cohort study, the prevalence of MCMA twinning was estimated using population-based data on MCMA twin pregnancies, collected between 2000 and 2013 from 11 Northern Survey of Twin and Multiple Pregnancy (NorSTAMP) maternity units. Pregnancy outcome at < 24 weeks' gestation, antenatal parameters and perinatal outcome (from ≥ 24 weeks to the first 28 days of age) were analyzed using combined data on pregnancies confirmed to be MCMA from NorSTAMP and the Southwest Thames Region of London Obstetric Research Collaborative (STORK) multiple pregnancy cohort for 2000-2013.

Results: The estimated total prevalence of MCMA twin pregnancies in the North of England region was 8.2 per 1000 twin pregnancies (59/7170), and the birth prevalence was 0.08 per 1000 pregnancies overall (singleton and multiple). Using combined data from NorSTAMP and STORK, the rate of fetal death (at < 24 weeks' gestation), including terminations of pregnancy and selective feticide, was 31.8% (54/170); the overall perinatal mortality rate was 14.7% (17/116), ranging from 69.2% at < 30 weeks to 4.5% at ≥ 33 weeks' gestation. MCMA twins that survived in utero beyond 24 weeks were delivered, usually by Cesarean section, at a median of 33 (interquartile range, 32-34) weeks of gestation.

Conclusions: In MCMA twins surviving beyond 24 weeks of gestation, there was a higher survival rate compared with in previous decades, presumably due to early diagnosis, close surveillance and elective birth around 32-34 weeks of gestation. High perinatal mortality at early gestations was attributed mainly to extreme prematurity due to preterm spontaneous labor. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Keywords: Northern Survey of Twin and Multiple Pregnancy (NorSTAMP); STORK collaboration; antenatal surveillance; monochorionic monoamniotic twins; perinatal mortality.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cesarean Section / statistics & numerical data
  • Cohort Studies
  • England / epidemiology
  • Female
  • Fetal Monitoring / methods
  • Fetal Mortality*
  • Gestational Age
  • Humans
  • Infant
  • Infant, Newborn
  • Live Birth / epidemiology
  • Male
  • Perinatal Mortality*
  • Population Surveillance
  • Pregnancy
  • Pregnancy, Twin / statistics & numerical data*
  • Premature Birth / mortality
  • Prenatal Care / methods*
  • Prevalence
  • Twins, Monozygotic / statistics & numerical data*
  • Ultrasonography, Prenatal
  • Young Adult