Timing of birth in multiple pregnancy

Area of Science:

• Perinatology
• Maternal-Fetal Medicine
• Obstetrics

Background:

• Perinatal mortality increases significantly in twins after 37 weeks gestation.
• Monochorionic twins exhibit a three-fold higher stillbirth risk compared to dichorionic twins throughout pregnancy.
• Near-term stillbirth rates are elevated even in low-risk monochorionic twin pregnancies.

Purpose of the Study:

• To evaluate the optimal timing for twin delivery based on chorionicity and fetal wellbeing.
• To compare stillbirth risks between monochorionic and dichorionic twin pregnancies.
• To inform clinical guidelines for managing twin gestations.

Main Methods:

• Analysis of large cohort studies on twin pregnancies.
• Comparison of stillbirth rates based on chorionicity (monochorionic vs. dichorionic).
• Assessment of risks associated with expectant management versus early delivery.

Main Results:

• Stillbirth risk increases significantly after 37 weeks for twins, unlike singletons after 42 weeks.
• Uncomplicated monochorionic twins show no significant stillbirth increase between 32-37 weeks, typically delivered at 37 weeks.
• Dichorionic twin stillbirth risk remains stable from 28-38 weeks, supporting expectant management until 38 weeks.

Conclusions:

• A differential delivery policy for monochorionic and dichorionic twins is justified.
• Uncomplicated dichorionic twins can be managed expectantly until 38 weeks.
• Preterm delivery decisions for discordant twins must balance the health of both fetuses, with lower thresholds for monochorionic twins due to higher risks.