Outcomes of pregnancies with more than one positive prenatal screening result in the first or second trimester

Objective: To describe adverse outcomes and fetal abnormalities in women with a positive prenatal screening result for more than one disorder. Study design: Study participants were drawn from a population of 452901 women pregnant with singletons entering the California Prenatal Screening Program in their first-trimester. Risk assessment was provided for trisomy 21 and trisomy 18 in the first-trimester and trisomy 21, trisomy 18, neural tube defects, and Smith-Lemli-Opitz syndrome in the second-trimester. Inclusion in this study required positive screening for more than one of the screened conditions and a completed outcome of pregnancy survey. Results: A total of 874 women met our study inclusion criteria. Over 25% of these pregnancies had a fetus with a chromosomal abnormality. Of the euploid pregnancies, 6.9% had a fetus with a major birth defect. Of the pregnancies with a fetus with neither a chromosomal abnormality nor a major birth defect, 9.3% ended in fetal demise. Overall, more than 50% of women with multiple positive screening results had either a fetus with a birth defect or a poor pregnancy outcome. Conclusion: Although it is rare to screen positive for more than one condition, such results indicate a very high risk for chromosomal abnormality, fetal demise, or structural abnormality.