Similarity of twins to singleton maternal serum alpha-fetoprotein ratio by race: no need to establish specific multifetal tables.
The purpose of this study was to assess the need for race-specific maternal serum alpha-fetoprotein (MSAFP) curves in twin gestations. MSAFP values were evaluated in 535 samples obtained from twin gestations. Results were grouped according to gestational age (from 15 to 20 weeks), as with our singletons. Separate median curves were determined for black and for white pregnancies. On average, the median serum alpha-fetoprotein (AFP) for twins was about twice (2.1 +/- 0.3) the median of singletons. MSAFP in blacks was commonly higher than in white pregnancies of comparable gestational age. Using a 4.5 multiple of the singleton median cutoff in twin white pregnancies, 3.9% of the results were defined as 'high', similar to the rate observed in singleton pregnancies. 'Low' results in twins were defined as AFP values lower than 1.0 multiples of the singleton median (in pregnancies of similar gestational age and race). About 7% of the serum samples for whites were defined as 'low' by this criteria. Data for blacks were comparable. Race-dependent median values should be used for MSAFP interpretation in twin as well as singleton pregnancies. 'High' and 'low' percentages are comparable to our large data bank of singleton pregnancies and seem to be adequate for interpretation of serum AFP in twins. Therefore, the race-specific singleton multiples are sufficient, obviating the need to build specific median curves for multifetal gestations.
Drugan
A
A
Department of Obstetrics and Gynecology, Hutzel Hospital/Wayne State University School of Medicine, Detroit, Mich 48201.
O'Brien
J E
JE
Gambino
R
R
Johnson
M P
MP
Evans
M I
MI
D044383:Black People; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000097:blood*; D044469:Racial Groups; D012016:Reference Values; D014427:Twins; D044465:White People; D000509:alpha-Fetoproteins / Q000032:analysis*
D000509:alpha-Fetoproteins