Fetal heart rate and umbilico-placental Doppler flow velocity waveforms in early pregnancies with a chromosomal abnormality and/or an increased nuchal translucency thickness

Fetal heart rate, umbilical artery pulsatility index, end-diastolicflow,nuchal translucency thickness and placental thickness were recordedin 250 women with a viable singleton pregnancy undergoing chorionicvillous sampling for fetal karyotyping at 11–14 weeksof gestation. The fetal karyotype was normal in 210 cases andabnormal in 40, including 21 with trisomy 21, 13 with trisomy18, three with triploidy, two with monosomy X and one with trisomy13. A total of 52 fetuses with a normal karyotype had a nuchaltranslucency 3 mm and were considered separately. There wasa stable and significant increase in the mean fetal heart ratein trisomy 21 pregnancies compared to controls. No significantdifference was found for the other variables between the groups.In chromosomally normal fetuses with an increased nuchal thickness,the development of fetal heart rate and compliance of the umbilico-placentalcirculation were within the normal ranges. Some fetuses withtrisomy 18 or triploidy had an increased resistance to bloodflow in the umbilical artery, which was probably due to abnormalplacental development.