Preterm delivery rate and fetal outcome in structurally affected twin pregnancies: a retrospective matched control study.

Data from 23 twin pregnancies with one structurally affected fetus were compared with data from 23 twin pregnancies with proven absence of structural fetal anomalies and matched for maternal age, parity, and year of delivery. The preterm delivery rate (< 37 weeks) was high in both groups but not significantly different (57 vs. 48 per cent). Perinatal mortality was significantly higher in the structurally affected twin pregnancies (65 vs. 9 per cent). In the affected twins, birth weight of the anomalous fetus was significantly lower than that of the normal co-twin. Since there was no difference in the incidence of maternal disease (hypertensive disorders, diabetes), it was concluded that the higher perinatal mortality was determined mainly by the nature of the anomaly and not by the preterm delivery rate.