Multiple marker screening in multifetal gestations: failure to predict adverse pregnancy outcomes

Area of Science:

• Maternal-Fetal Medicine
• Reproductive Endocrinology
• Clinical Chemistry

Background:

• High maternal serum alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) are associated with adverse outcomes in singleton pregnancies.
• The predictive value of these markers in multifetal gestations is less understood.

Purpose of the Study:

• To determine if the association between high maternal serum AFP or HCG and adverse pregnancy outcomes extends to multifetal gestations.
• To evaluate the utility of multiple marker screening in predicting adverse outcomes in twin and higher-order pregnancies.

Main Methods:

• Maternal serum AFP and HCG levels were measured in 207 multifetal pregnancies.
• High values were defined as > 4.5 MoM for AFP and > 4.0 MoM for HCG.
• Results were correlated with adverse outcomes including premature delivery, stillbirth, and termination for fetal anomalies.

Main Results:

• Maternal serum AFP levels were slightly higher in pregnancies with adverse outcomes compared to normal outcomes (3.4 vs. 2.5 MoM, NS).
• High AFP levels occurred in 6% of adverse outcome pregnancies and 4% of uncomplicated gestations (NS).
• High HCG values (5% of cases) were exclusively associated with normal outcomes. Multiple marker screening indicated aneuploidy risk in 9% of patients, all of whom were euploid.

Conclusions:

• Maternal serum screening in multifetal pregnancies is confounded by the varying contributions of each fetus.
• Abnormal screening results in multifetal gestations do not reliably predict adverse pregnancy outcomes.
• Current multiple marker screening protocols may require adjustment for multifetal pregnancies.