Outcome of twin gestations following sonographic demonstration of two heart beats in the first trimester

We conducted a prospective study to assess pregnancy outcome following a first‐trimester ultrasound examination demonstrating intrauterine twins with heart beats. Our study population included 68 cases of twin gestations in which a first‐trimester scan demonstrated two heart beats. We correlated pregnancy outcome with placentation type, gestational age, maternal age, and method of conception. There were 59 dichorionic and nine monochorionic gestations. Twenty‐six of the dichorionic pregnancies resulted from treatment for infertility. Among all 68 cases, 54 (79%) delivered viable twins, eight (12%) delivered one infant, and six (9%) delivered none. The outcome in dichorionic gestations (83% delivered twins, 12% singletons, 5% none) was significantly better than in monochorionic gestations (56%, 11%, 33%, respectively) (p < 0.05). Among dichorionic twins, pregnancy outcome was worse in twins initially identified on a 6–7.9 week ultrasound examination (74% delivered twins, 21% singletons, 6% none) as compared to those identified at 8–13 weeks (96%, 0%, 4%, respectively) (p < 0.05). The outcome in dichorionic gestations was worse in women over 35 compared to those under 35 (p < 0.05), and those with treatment for infertility compared to those who conceived naturally (p = 0.05). These results provide prognostic information about outcome of twin pregnancies scanned in the first trimester as a function of chorionicity, gestational age, maternal age, and method of conception.