INSULIN-LIKE-GROWTH-FACTOR BINDING PROTEIN-3 IN THE DETECTION OF FETAL DOWN-SYNDROME PREGNANCIES

Objective: To study the usefulness of maternal serum insulin-like grow th factor binding protein-3, a potential cell growth inhibitor, in sec ond trimester prenatal screening for fetal Down syndrome. Methods: Thr ee hundred and forty-two samples from normal pregnancies and nine feta l Down syndrome pregnancies were analyzed for insulin-like growth fact or binding protein-3 levels by radioimmunoassay. Data were converted t o multiples of median (MoM) and analyzed statistically to compare the differences between control and Down syndrome pregnancies. Results: Th e mean insulin-like growth factor binding protein-3 MoM of Down syndro me-affected pregnancies (1.09) was significantly higher than that of t he normal pregnancies (1.00) (P < .01). Insulin-like growth factor bin ding protein-3, in combination with maternal serum alpha-fetoprotein ( MSAFP), hCG, and maternal age, detected 89% of Down syndrome pregnanci es at a screen positive rate of 2.1%. This compares favorably to the s tandard combination of MSAFP, hCG, and unconjugated estriol (E3), whic h had a 66.7% Down syndrome detection rate and a 4.1% screen positive rate in our study samples. Conclusion: This retrospective analysis sug gested that the inclusion of insulin-like growth factor binding protei n-3 into the triple screen program to replace unconjugated E3 might en hance the detection rate of fetal Down syndrome pregnancies. These dat a need to be confirmed by a larger prospective study. (C) 1998 by The American College of Obstetricians and Gynecologists.