The applicability of multiple of median in second trimester maternal serum for prenatal screening

Objective To study the necessity of adjusting the multiple of median (MoM) of alpha fetoprotein (AFP),human chorionic gonadotropin β (β-hCG)and unconjugated estriol (uE3) in screening the second trimester of pregnancy for Down syndrome or other birth disfigurements in Jiading region. Methods The gestational age-specific median of maternal serum markers AFP,β-hCG and uE3 were calculated by means of regression method in 1298 pregnant women. Regression functions for adjustment of MoM by weight were established. Results There was no correlation between pregnant week and MoMs of markers mentioned above. Before the adjustment by weight,the median level of AFP was 16.4% lower,β-hCG was 14.1% higher and uE3 was 6.3% higher than those of Caucasian provided by the TCSoft software respectively. The MoM median calculated by the software were 0.78 for AFP,1.02 for β-hCG and 1.03 for uE3,but when the AFP,β-hCG and uE3 MoM levels were converted to weight-adjusted levels,the MoM median were 0.99 (P 0.05),0.98 and 0.98 (P0.05). Conclusions There is a difference of median weight-adjusted MoM levels between the data obtained from the pregnant women in the Jiading district and from TCSoft software (designed by Shanghai Tengcheng Medical Tech-info Co.,Ltd),therefore the screening laboratory should establish their own suitable criteria level.