We carried out a preliminary study to compare the nasal bone length (NBL) and biparietal diameter/NBL (BPD/NBL) ratio between the Japanese and white populations.Methods
Three hundred and fifty nine (359) singleton fetuses of healthy Japanese couples were examined from June 2004 to October 2005. NBL was measured by the strict midsagittal section. The reference range of NBL was established from cross-sectional data between 15 and 25 weeks' gestation.Results
The success rate of obtaining reliable NBL was 93% (333/356). There were 330 fetuses (93%) available for constructing a reference range from the population. The median NBL increased from 3.2 mm at 15 weeks' to 7.6 mm at 25 weeks' gestation. The median of BPD/NBL ratio was 9.01.Conclusions
We demonstrated that NBL was significantly shorter and BPD/NBL was significantly greater in the Japanese population than those in the white and black populations.