Weight-correction formula for maternal serum screening for Down syndrome in Taiwan.

BACKGROUND AND PURPOSE: This study examined the relationship between maternal weight and serum marker concentrations (alpha-fetoprotein [AFP] and human chorionic gonadotropin [hCG]) to develop a weight-correction formula for second-trimester Down syndrome screening in Taiwan. METHODS: We conducted a prospective observational study based on data from 18, 016 pregnant Taiwanese women who participated in a second-trimester Down syndrome screening program at Taiwan Adventist Hospital. The relationship between maternal weight and the multiple of median (MoM) concentrations of serum markers was analyzed using two methods; one involved all the observational data (all point method), while the other involved only the median concentrations at various gestational ages (median regression method). In each method, several statistical approaches were used, including simple-linear, reciprocal, quadratic, and log-transformation linear regression. RESULTS: The correlation between maternal body weight and serum marker concentrations using the all point regression method was very poor, while the median regression method achieved a good fit. The reciprocal regression analysis had the best fit between AFP MoM concentration and maternal weight, while the best fit between hCG MoM concentration and maternal weight was achieved with quadratic regression analysis. CONCLUSION: The present study has developed a race-specific weight-correction formula for Taiwanese women. This formula is expected to be helpful in second-trimester Down syndrome screening programs in Taiwan.