Outcome of twin gestations with a single anomalous fetus

Our goal was to determine whether the presence of one anomalous fetus in a twin gestation affects pregnancy outcome when compared with twin pregnancies without fetal anomalies.

Maternal and neonatal data from 970 twin pregnancies delivered from 1988 to 1995 were collected. Three groups of twin gestations were identified: one fetus with a major anomaly (n = 18), one fetus with a minor anomaly (n = 38), and both fetuses without anomalies (n = 914).

Maternal demographic characteristics (age, race, and antepartum complications) were similar among the groups. There was no difference in neonatal outcome (gestational age at delivery, birth weight, cord pH, sepsis, and death) in the minor anomaly and no anomaly groups. There were significant differences between the major anomaly group and the no anomaly group in gestational age at delivery (32.9 vs 35.6 weeks, p < 0.05), birth weight at delivery (1759 vs 2291 gm, p < 0.05), hospital days (41 vs 13 days, p < 0.05), and perinatal death of the anomalous fetus (278/1000 vs 10/1000). Except for total days in the hospital, there was no difference in neonatal morbidity or mortality for the normal fetus when compared with the minor group or the no anomaly group.

The presence of a fetus with a major anomaly in a twin gestation increases the risk of preterm delivery. The neonatal outcome of the nonanomalous fetus does not appear to be affected by the anomalous fetus.