Monochorionic diamniotic infants without twin-to-twin transfusion syndrome

Area of Science:

• Perinatology
• Maternal-Fetal Medicine
• Twin Gestation Studies

Background:

• Monochorionic-diamniotic (MoDi) twins occur in 0.3% of pregnancies.
• Twin-to-twin transfusion syndrome (TTS) affects 20% of MoDi twins, leading to high perinatal morbidity and mortality.
• MoDi twins without TTS are more common (80%) but less studied.

Purpose of the Study:

• To investigate perinatal morbidity and mortality in 74 MoDi twin sets without TTS.
• To compare outcomes of MoDi twins without TTS to 38 MoDi twin sets with TTS.

Main Methods:

• Chorionicity determined by gender and placental examination.
• Gestational age (GA) assessed via sonography and pediatric examination.
• TTS diagnosed clinically and sonographically; discordance defined by >20% birth weight difference; fetal growth restriction assessed using twin-specific nomograms.

Main Results:

• MoDi twin pregnancies without and with TTS showed similar demographics, live births, preeclampsia history, fetal distress, and cesarean delivery rates.
• Significant differences (p<0.01) were observed in discordant pregnancies (36% vs. 79%), GA at delivery (32 vs. 29 weeks), intrauterine growth restriction (39% vs. 89%), and neonatal mortality (12% vs. 36%).
• Among MoDi twins without TTS, concordant (47 sets) and discordant (27 sets) groups were clinically similar.

Conclusions:

• MoDi twins without TTS exhibit high rates of birth weight discordance, fetal growth restriction, fetal distress, prematurity, and cesarean delivery.
• Despite low perinatal mortality, the prevalence and short- and long-term impacts of fetal and neonatal morbidities in MoDi twins without TTS warrant clinical attention.