RESUMEN
<p><b>OBJECTIVE</b>To establish the median values for second trimester biomarkers in Weihai region, and to assess its value for improving the performance and efficiency of prenatal screening.</p><p><b>METHODS</b>Maternal serum alpha-fetoprotein (AFP) and free beta human chorionic gonadotropin (Free beta-hCG) were determined for 24 400 pregnant women at 105 to 146 gestational days. A regression equation was derived after adjusting for different gestational ages. The median values were further adjusted with body weight.</p><p><b>RESULTS</b>The median values of AFP and Free beta-hCG were respectively 6% and 24% higher than those embedded in a 2T software. After adjusting with gestational age and weight, there is a significant difference in multiple of the median (MoM) of serum biomarkers between local population and that embedded in the 2T model.</p><p><b>CONCLUSION</b>To establish the median values for different gestational ages for local region may help to improve the efficiency of prenatal screening.</p>