Maternal serum alpha-fetoprotein prenatal screening for Down syndrome.

The relationship between maternal serum alpha-fetoprotein (MSAFP) levels, maternal age and Down syndrome risk factors were studied in the greater Birmingham and North Alabama areas. After adjustment for race and maternal weight, 3.84 percent of women in this study were determined to have Down syndrome risk factors equal to or greater than that of a 35 year old woman with a normal pregnancy. Maternal weight adjustment was of special importance, reducing the number of MSAFP values considered low from 5.12 percent to 3.40 percent. The use of race and area specific medians was also important in the use of prenatal MSAFP screening for Down syndrome affected pregnancies.