Maternal serum a-fetoprotein levels in pregnancies among black and white women with fetal open spina bifida: A United States Collaborative Study

Abstract

In the present study second-trimester maternal serum alpha-fetoprotein levels were analyzed from 146 pregnancies associated with fetal open spina bifida to identify whether affected pregnancies from the black population were associated with higher maternal serum alpha-fetoprotein levels than their white counterparts. Pregnancies in black women not affected by open spina bifida are already known to have higher maternal serum alpha-fetoprotein levels. All of the cases were analyzed with gestational ages assigned by last menstrual period, and all maternal serum alpha-fetoprotein values were expressed as multiples of the median, to correct for differences in gestational age and assay among the 15 centers reporting data. The levels from affected pregnancies in white and black women fit log Gaussian distributions, with medians of 3.10 and 4.37 multiples of the median, respectively, on the basis of singleton, unaffected, white pregnancy medians. These results support adjustment of maternal serum alpha-fetoprotein values for race in black women; in addition, if a screening program's policy is to screen at a comparable risk in the two races, a higher maternal serum alpha-fetoprotein multiple of the median cutoff would be justified for black women.