Final answer:
MSAFP levels in multiple gestations are typically higher than in singleton pregnancies, reflecting the combined protein production from each fetus. This elevation is expected and considered in the interpretation of prenatal screening results.
Step-by-step explanation:
The question concerns the comparison of maternal serum alpha-fetoprotein (MSAFP) levels in multiple gestations as opposed to singleton pregnancies. In the context of pregnancy, MSAFP screening is a part of prenatal testing that can indicate certain fetal conditions. Typically, MSAFP levels in multiple gestations are higher in comparison to singleton pregnancies. This is because MSAFP, a protein produced by the fetal liver and found in the amniotic fluid and mother's blood, is secreted by each fetus in a multiple gestation pregnancy, thus elevating the overall levels.
Therefore, during prenatal screenings, practitioners expect to see an approximate doubling of MSAFP levels for twins and a tripling for triplets when compared to singleton pregnancies. It is crucial to account for the number of fetuses when interpreting MSAFP results to avoid false positives for conditions such as neural tube defects or abdominal wall defects. High levels of MSAFP in a singleton pregnancy may require additional testing, while elevated levels in multiple gestations may be considered normal.