Maternal serum alpha-fetoprotein screening for chromosomal abnormalities: a prospective study in women aged 35 and older.
OBJECTIVE
Our purpose was to determine the detection and false-positive rates for maternal serum alpha-fetoprotein measurement to screen for fetal Down syndrome and other chromosomal abnormalities in women > or = 35 years old.


METHODS
A total of 3896 women had serum maternal serum alpha-fetoprotein levels measured routinely before amniocentesis for the indication of advanced maternal age.


RESULTS
Eighty-five percent (28/33) of fetal Down syndrome pregnancies had second-trimester risks of > or = 1:270 on the basis of a combination of maternal serum alpha-fetoprotein measurement and maternal age. Risks were also > or = 1:270 in 63% of the unaffected pregnancies. Sex chromosome aneuploidies, translocations, and other nonautosomal chromosome abnormalities in this study population were not associated with altered maternal serum alpha-fetoprotein levels; 51.9% (14/27) of these, however, were also assigned risks of > or = 1:270.


CONCLUSIONS
Maternal serum alpha-fetoprotein screening is more accurate than age alone for assigning individual Down syndrome risk in pregnant women > or = 35 years old. Counseling for women in this age group should include information regarding the lower sensitivity of maternal serum alpha-fetoprotein screening for detecting fetal Down syndrome and other chromosomal abnormalities (especially sex chromosome aneuploidies) compared with offering amniocentesis to these women.
Rose
N C
NC
Univeristy of Pennsylvania Medical Center, Philadelphia 19104.
Palomaki
G E
GE
Haddow
J E
JE
Goodman
D B
DB
Mennuti
M T
MT
D000328:Adult; D002869:Chromosome Aberrations / Q000175:diagnosis*; D025063:Chromosome Disorders; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008423:Maternal Age; D018566:Pregnancy, High-Risk; D011446:Prospective Studies; D000509:alpha-Fetoproteins / Q000032:analysis*
D000509:alpha-Fetoproteins