SERUM TRIPLE-MARKER SCREENING IN IN-VITRO FERTILIZATION AND NATURALLYCONCEIVED PREGNANCIES

Objective: To determine whether results of second-trimester maternal s erum triple-marker screening for Down syndrome and open neural tube de fects in singleton pregnancies conceived from in vitro fertilization ( IVF) differ from those of pregnancies conceived spontaneously. Methods : The screen-positive rates and triple-marker levels of patients conce iving singleton pregnancies by IVF were compared to age-adjusted stand ards. Results: Sixty-nine singleton IVF pregnancies with maternal seru m screening were identified. Twenty-one (30.4%) of the 69 IVF singleto n pregnancies had a positive screen for Down syndrome compared with a 14.4% expected screen-positive rate for the maternal age distribution in our observed sample (P = .013). The screen-positive rate for open n eural tube defects in the measured population was similar to anticipat ed values based on historic controls (5.8% in IVF patients versus 5.3% in the total population). The median levels of the triple markers wer e 0.95 multiples of the median (MoM) for alpha-fetoprotein (AFP), 0.90 MoM for unconjugated estriol (E3), and 1.22 MoM for hCG. Conclusion: The increased hCG levels as well as the slightly lower AFP and unconju gated E3 levels may contribute to the higher Down syndrome screen-posi tive rate in this IVF singleton population. These results may be due t o the number of embryos transferred, the maternal hormonal environment of the IVF process, or other factors. Pregnancies conceived by IVF ma y be twice as likely to have a positive maternal serum screening test. As additional data are collected, corrected standards should be deter mined. (C) 1997 by The American College of Obstetricians and Gynecolog ists.