Distribution of PAPP-A and total hCG between 11 and 13 weeks of gestation in Japanese pregnant women

Objectives: To establish the reference values for PAPP-A and total hCG between 11 and 13 weeks of gestation for the use of risk assessment of fetal aneuploidy in Japanese pregnant women. Methods: A multicenter prospective study was conducted. The subjects included only Japanese pregnant women with viable singleton who requested the first trimester combined (nuchal translucency and maternal serum marker) screening for fetal aneuploidy. Reference values of PAPP-A and total hCG in Japanese population were made and compared with them in Caucasian. Results: Overall 1,751 Japanese pregnant women were analyzed. Median vales of maternal serum concentration in Japanese pregnant women from 11 + 0–13 + 6 weeks’ gestation were ranged from 3.01 to 9.51 mIU/mL for PAPP-A and from 70.2 to 58.3 IU/mL for total-hCG, respectively. Regression curve of median maternal serum PAPP-A and total-hCG concentration against gestational days are significantly higher in Japanese comparing with Caucasian. At most distant values, Japanese serum concentration indicated 1.45 MoM for total-hCG and 1.70 MoM for PAPP-A based on Caucasian regression curves. Conclusion: A modification of the equations by specific reference values is necessary for Japanese pregnant women at the risk assessment of chromosomal abnormalities using the first trimester maternal serum marker.