Crown-rump length in chromosomally abnormal fetuses at 10 to 13 weeks' gestation.

Abstract

Our purpose was to investigate whether fetuses with aneuploidies demonstrate evidence of growth retardation during the first trimester. This was a retrospective, cross-sectional study of singleton pregnancies undergoing fetal karyotyping at 10 to 13 weeks' gestation. Measurements of crown-rump length in 135 chromosomally abnormal fetuses were compared with those in 700 chromosomally normal fetuses. The median crown-rump length of fetuses with trisomy 18 (n = 32) was significantly reduced. In contrast, in fetuses with trisomy 21 (n = 72), trisomy 13 (n = 11), 47,XXX (n = 6), 47,XXY (n = 6), 45,X (n = 5), and triploidy (n = 3) the crown-rump length was not lower than normal. At 10 to 13 weeks' gestation fetuses with trisomy 18 are growth retarded, whereas in trisomy 21, trisomy 13, and sex chromosome aneuploidy growth is normal.