Nuchal translucency thickness in fetuses with chromosomal translocation at 11-12 weeks of gestation.

OBJECTIVE: To investigate differences in nuchal translucency thickness among fetuses in which either parent is a balanced chromosome translocation carrier.
METHODS: A prospective observational study was conducted with 98 pregnant women in the first trimester. Each had been advised to undergo chorionic villous sampling for fetal karyotyping for the indication of parental balanced chromosomal translocation. Fetal nuchal translucency measurement was performed before chorionic villous sampling. Nuchal translucency thickness was compared among fetuses with 3 kinds of karyotypes: normal, balanced translocation, and unbalanced translocation.
RESULTS: There were no differences in maternal age, gestational age, parity, and number of previous miscarriages among pregnancies with normal karyotype, balanced chromosomal translocation, and unbalanced chromosomal translocation. A significantly greater nuchal translucency thickness was shown in the unbalanced chromosomal translocation group (2.9 +/- 1.2 mm) compared with both the balanced chromosomal translocation group (1.0 +/- 0.6 mm; P < .001) and the normal karyotype group (1.0 +/- 0.8 mm; P < .001). No statistically significant difference in nuchal translucency thickness was found between the balanced chromosomal translocation group and normal karyotype group (P = .991). Nuchal translucency thickness did not differ significantly between unbalanced chromosomal translocation dependent on paternal origin and that dependent on maternal origin (P = .611).
CONCLUSION: In fetuses with unbalanced chromosomal translocation, nuchal translucency thickness tends to be greater, and thus nuchal translucency measurement might be considered part of the investigation for pregnancies marked by a parental balanced chromosomal translocation.