904: Do chronic comorbidities increase the risk of a high no-call rate in non-invasive prenatal screening?

Abstract

Chronic maternal comorbidities including sickle cell disease (SCD), chronic hypertension (CHTN) and pregestational diabetes may cause vasculopathies that lead to tissue hypoxia and subsequently an increase in maternal cell necrosis which create a dilutional effect in fetal fraction on non-invasive prenatal screening (NIPS). We sought to evaluate the impact of chronic maternal comorbidities on the NIPS no-call rate. We hypothesized that chronic maternal comorbidities would increase the no-call rate for NIPS. This was a retrospective nested cohort study. A cohort was assembled of women with singleton pregnancy who obtained NIPS from June 2016 to August 2017 in a tertiary care center and a cohort of women with SCD and NIPS from Natera, Inc. laboratory. The primary outcome was no-call rate due to low fetal fraction. Women were classified based on the trimester. And differences in fetal fraction percent across trimesters were compared using the Kruskal- Wallis test. Fisher’s exact test was used to compare no-call rates for SCD, chronic hypertension and pregestational diabetes with Those of women who didn’t have these comorbidities. The potential association between no-call rate and maternal comorbidities, gestational age and weight was evaluated using logistic regression. The cohort consisted of 521 women. The median fetal fraction for first, second and third trimester were 6.8%, 8.9% and 9.2% (p<0.05). No-call rates in the first, second and third trimester were 10.6%, 3.9% and 1.8% (p<0.05). Overall no-call rate is significantly higher among women with comorbidities (table 2). In the regression model, SCD and CHTN were significant predictors of a no-call report in the first trimester (p<0.05), while SCD and weight were significant predictors of a no-call report in the second trimester (p<0.05). No predictors were significant in the third trimester. CHTN and SCD appear to be significantly associated with an increase in the no-call rate during the first trimester. Providers need to consider chronic maternal comorbidities during counseling for aneuploidy screening.View Large Image Figure ViewerDownload Hi-res image Download (PPT)