Management of twin pregnancies with fetal trisomies

Objective To examine options of management and outcome of twin pregnancies affected by fetal trisomies. Design Retrospective study. Setting Research Centre for Fetal Medicine. Population Twenty‐seven twin pregnancies affected by fetal trisomy. Methods A computer search was made of our database for twin pregnancies concordant or discordant for trisomies. The data were reviewed for gestation at diagnosis of the chromosomal abnormality, management and pregnancy outcome. Main outcome measures Pregnancy management and outcome in relation to type and gestation at diagnosis of the trisomies. Results There were seven cases where both fetuses were trisomies and in these the parents opted for termination of pregnancy; termination was also performed in another pregnancy where one fetus had trisomy 18 and the chromosomally normal co‐twin had a major facial cleft. In 19 cases one fetus had either trisomy 21 ( n = 14 ) or trisomy 18 ( n = 5 ) and the other was normal. Selective fetocide was carried out in 13 of 14 pregnancies discordant for trisomy 21 and in one of the five with trisomy 18. In the four cases discordant for trisomy 18 that were managed expectantly, the trisomic baby died in utero or in the neonatal period, whereas the normal co‐twin was liveborn at 33 to 40 weeks (median 37). In the 14 cases of selective fetocide, the chromosomally normal co‐twin was live born at 24 to 41 weeks of gestation (median 38), and there was a nonsignificant inverse correlation between the gestation at fetocide and gestation at delivery. Conclusions In twin pregnancies discordant for fetal trisomies the main determinant in deciding whether to perform selective fetocide or adopt expectant management is the degree of lethality of the chromosomal defect.