(1127) Prenatally Diagnosed Genetic Anomalies, Anticipated Phenotypes, and Pregnancy Outcomes

Phenotypic severity ranges broadly among genetic anomalies and should inform decisions about pregnancy termination. Our objective was to explore phenotype severity and pregnancy outcomes in those with abnormal genetic results.

Study Design:

This is a retrospective cohort study at a tertiary care center from 2016-2022. Pregnant patients who underwent invasive testing with abnormal results were included. Those with incomplete data or miscarriages were excluded. Phenotypes were categorized into “Severe” (e.g. Trisomy 13/18, OI Type II) “Moderate” (e.g. Trisomy 21, Noonan Syndrome), “Mild” (e.g. sex chromosome aneuploidy, Stargardt Disease), and “Unknown” (e.g. copy number variant of unknown significance) based on anticipated degree of cognitive impairment, morbidity and longevity. All patients underwent post-test genetic counseling. Analysis was done with Chi-square, Fisher Exact, or T-Test as appropriate.

Results:

202 patients were included. Demographic information and the distribution of diagnoses and phenotypes between pregnancies that were terminated vs continued are in Table 1.  Patients who underwent termination were more likely to undergo CVS vs amniocentesis (71% vs 38%) (p< 0.001). The overall rate of abortion following prenatal diagnosis was 64.8%. Autosomal trisomy was the most common diagnosis and was more common in pregnancies undergoing termination (50.4% vs 5.6%) (p< 0.001). There was a strong correlation between phenotype severity and the decision to undergo abortion. The rates of abortion were 92.8%, 90.1%, and 60.4% for those with severe, moderate, and mild phenotypes, respectively (p< 0.001). Only 15.6% of those with an uncertain phenotype terminated the pregnancy.

Conclusion:

In patients with prenatal diagnosis of genetic anomalies, we saw a strong correlation between phenotype severity and the rate of pregnancy termination. This highlights the importance of appropriate genetic counseling following prenatal diagnosis. Rates of termination were high even with milder phenotypes, indicating that most individuals in our population who choose invasive testing would consider abortion.