[Perinatal outcome of discordant twin pregnancies]

To discuss peripartum obstetrics events and perinatal outcomes of discordant twin pregnancies.

Discordant growth was defined as the intrapair difference in birth weight more than 20%. Ninety-six discordant twin pregnancies (observed group) and 349 concordant ones (control group) were compared in pregnant complications and perinatal outcomes.

No difference of maternal age, chorionicity, methods of conception and fetal gender were found between two groups. Observed group had a higher incidence of late abortion (13.5% vs 4.3%, P < 0.05), polyhydramnios (22.9% vs 10.0%, P < 0.01), twin-twin transfusion syndrome (9.4% vs 1.4%, P < 0.01), placental abruption (5.2% vs 1.1%, P < 0.05), perinatal death (22.9% vs 4.4%, P < 0.01) and of fetal malformation (5.2% vs 1.3%, P < 0.01) than control group. In observed group, perinatal death was higher in smaller twin than in larger one (30.2% vs 15.6%, P < 0.05). The incidences of perinatal death were 4.4%, 11.0% and 41.9% and fetal malformation were 1.3%, 5.1% and 5.4% when the discordance was < or = 20%, 20%-30%, and > or = 30%, respectively (P < 0.05).

Discordance places twins at increased risk for late abortion, premature delivery, polyhydramnios, twin-twin transfusion syndrome, placental abruption, perinatal death and fetal malformation. The smaller twin and great discordance are risk factors for poor outcomes. Chorionicity, methods of conception and fetal gender are not responsible for discordant growth.