Similarity of Twins to Singleton Maternal Serum Alpha-Fetoprotein Ratio by Race: No Need to Establish Specific Multifetal Tables

Abstract

The purpose of this study was to assess the need for race-specific maternal serum α-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 α-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.

Multiple Marker Screening in Multifetal Gestations: Failure to Predict Adverse Pregnancy Outcomes

“…These results imply that there is no need for separate and specific medians for twins, since those can be derived from the much larger databank of sin gleton pregnancies. This conclusion is sub stantiated by Wald et al [10] as well as by our previous study [8] on maternal serum AFP screening as a single marker in twins.…”

“…In a previous study [8], we evaluat ed maternal serum AFP screening (as single marker) in multifetal gestations and conclud ed that the maternal serum AFP level in twins is about twice that observed in singleton preg nancies and the effect of race is similar, ob viating the need to establish specific medians for multifetal gestations. In this study, we attempt to assess whether the association that has been reported in singleton pregnancies of abnormally high AFP or HCG levels in mater nal serum with adverse pregnancy outcome applies also the multifetal gestations.…”

Maternal hormone levels among populations at high and low risk of testicular germ cell cancer

“…With some exceptions (Macri et al, 1976;Milunsky et al, 1980), the majority of studies have reported a higher level of weight-adjusted AFP among black mothers than white mothers (Crandall et al, 1983;Johnson, 1985;Baumgarten, 1986;Macri et al, 1987;Drugan et al, 1993;Benn et al, 1997;O'Brien et al, 1997). Ethnic differences in AFP levels during third trimester, however, have not been thoroughly studied.…”

Reconsidering Race Adjustment in Prenatal Alpha-Fetoprotein Screening

“…published several article in the 1990s (none cited by Burns et al) using a database of more than 200,000 cases obtained from Metpath–Corning Clinical Labs (now Quest Diagnostics) and reached a completely opposite conclusion for race. 2–9 Our data showed that optimal screening performance in the United States required four separate databases, defined by White, Black, Hispanic, and Asian race. 2,3,6 Furthermore, the simple 10% adjustment factor (commonly used for Black patients) was insufficient, because the slopes of the curves were not actually parallel.…”