Relationship between False Positive Screening Results of Down Syndrome and Adverse Pregnancy Outcomes.

Background: Maternal serum sample screening in the first and second trimesters has been commonly used to identify women who are at risk of fetal trisomy 21. In addition, these serum markers are associated with adverse perinatal outcomes. Hence, the present study was conducted to determine the relationship between false positive screening results of Down syndrome and adverse pregnancy outcomes. Material and Methods: This prospective, two-group, cohort study was conducted on 608 pregnant women who had undergone fetal contingent screening. They were selected through convenience sampling in the twentieth week of pregnancy and were followed up until delivery. The raw Odd Ratios (OR), Relative Risk (RR), and adjusted OR of adverse pregnancy outcomes were calculated in the false positive and true negative groups. Results: The adjusted OR of developing preeclampsia was 1.98 (95%CI: 1.14-3.42), and its RR was 2.13 (95%CI: 1.34-3.38) times higher in the false positive group. Moreover, the adjusted OR of Small for Gestational Age (SGA) was 2.80 (95%CI: 1.76-4.47), and its RR was 2.28 (95%CI: 1.54-3.36) times higher in the false positive group. The adjusted OR of Low Birth Weight (LBW) was 3.34 (95%CI: 1.97-5.64), and its RR was 2.65 (95%CI: 1.72-4.11) times higher in the false positive group. In addition, no significant difference was observed between false positive and true negative groups in terms of preterm birth. Conclusions: Women with a false positive fetal screening test result are more likely to suffer from preeclampsia, SGA, and LBW and require planned prenatal care.