Reference centile chart for fetal nuchal translucency, maternal serum PAPP-A and free beta hCG

Abstract

Objective: To create reference centile chart of fetal nuchal translucency, maternal serum pregnancy associated plasma protein-A (PAPP-A) and maternal serum free beta human chorionic gonadotropin (beta-hCG) in order to predict preliminarily Down syndrome in Thai fetuses during 10-14 weeks of gestation. Material and Method: This was a prospective, descriptive cohort study. From 1 January 2004 to 31 December, 2006, a total of 1,000 pregnant women during 10-14 weeks of gestation were participated in the present study. Pregnancy outcomes were reviewed from the records. The excluded cases were chromosomal and major structural abnormalities, twin pregnancy and cases resulting in miscarriage or intrauterine death. All women had a scan for nuchal translucency (NT) and had blood taken for measurement of maternal serum PAPP-A and free beta-hCG level. Results: The mean NT was 1.6 ± 0.8 mm (range 0.3-14 mm). The 5 th, 50th and 95th centile of PAPP-A and free beta-hCG during 11-14 weeks of gestation were 1.54-69, 14-28, 51-57 and 24.8-17, 78-47, 181.6-126.5 mIU/ mL, respectively. The distribution and the 5% and 95%, lower and upper limits of NT, PAPP-A and free betah-CG was presented. Conclusion: The present study shows that NT measurements increase with increasing gestational age. The mean serum PAPP-A rises and the mean serum-free beta hCG decreases from 10 to 14 weeks of gestation in normal Thai fetuses. These results can be used for reference value to predict fetal Down Syndrome.