The outcome of monochorionic diamniotic twin gestations in the era of invasive fetal therapy: a prospective cohort study

Objective The purpose of this study was to document pregnancy and neonatal outcome of monochorionic diamniotic twin pregnancies. Study Design This observational study describes a prospective series included in the first trimester in 2 centers of the Eurotwin2twin project. Results Of the 202 included twin pairs, 172 (85%) resulted in 2 survivors, 15 (7.5%) in 1 survivor, and 15 (7.5%) in no survivors. The mortality was 45 of 404 (11%), and 36 of 45 (80%) were fetal losses of 24 weeks or less, 5 of 45 (11%) between 24 weeks and birth, and 4 of 45 (9%) were neonatal deaths. Twin-to-twin transfusion syndrome (TTTS) occurred in 18 of 202 (9%). The mortality of TTTS was 20 of 36 (55%), which accounted for 20 of 45 (44%) of all losses. Severe discordant growth without TTTS occurred in 29 of 202 (14%). Its mortality was 5 of 58 (9%), which accounted for 5 of 45 (11%) of all losses. Major discordant congenital anomalies occurred in 12 of 202 (6%). Of the 178 pairs that continued after 24 weeks, 10 (6%) had severe hemoglobin differences at birth. After 32 weeks, the prospective risk of intrauterine demise was 2 in 161 pregnancies (1.2%; 95% confidence interval, 0.3-4.6). Conclusion Of the monochorionic twins recruited in the first trimester, 85% resulted in the survival of both twins, and 92.5% resulted in the survival of at least 1 twin. Most losses were at 24 weeks or less, and TTTS was the most important cause of death. After 32 weeks, the risk of intrauterine demise appears to be small.