Triple-Analyte Screening for Down Syndrome: More False-Positives in IVF Patients

In the U.S., pregnant women younger than 35 are screened for Down syndrome fetuses through measurement of serum-analyte levels (human chorionic gonadotrophin [hCG], α-fetoprotein [AFP], and unconjugated estriol [uE₃]); if the results indicate increased risk, such women are offered invasive diagnostic procedures (chorionic villus sampling or amniocentesis). Women who become pregnant after undergoing in vitro fertilization have elevated hCG levels long after ovulation stimulation and, thus, have more false-positive screening results. Such elevated hCG levels could be related to drugs that are given to induce ovulation during IVF. Therefore, these investigators measured hCG, AFP, and uE₃ levels in IVF patients who did not receive ovulation-ind…