Expectant management of twin pregnancies discordant for anencephaly

To study the clinical course and perinatal outcome of twin pregnancies discordant for anencephaly, without selective termination. We conducted a descriptive retrospective study of 14 cases of dichorionic twin pregnancies discordant for anencephaly, which were managed expectantly in five Israeli perinatal centers. None of the patients miscarried. The mean gestational age at delivery was 35.9 ± 2.8 weeks (range 29–39). Only three patients (21%) delivered before 35 weeks' gestation. Polyhydramnios occurred in six of the anencephalic amniotic sacs. Nevertheless, most occurrences were mild and none necessitated therapeutic amniocentesis. The mean birth weight of the normal fetus was 2610 ± 690 g (range 1100-3200). One apparently normal twin had a cardiac anomaly and died shortly after birth, and one was electively delivered at 33 weeks because of severe intrauterine growth retardation and subsequently developed cerebral palsy. The rest had normal short- and long-term outcomes. Expectant management of a twin gestation discordant for anencephaly diagnosed at the second trimester is associated with a favorable outcome for the unaffected fetus.