265: Adverse perinatal outcomes and cell free DNA no calls: Beyond low fetal fraction

Abstract

Adverse perinatal outcomes have been associated with cell free DNA (cfDNA) low fetal fraction (LFF) and LFF has been associated with “no call” results (NC) on cfDNA. We aimed to describe neonatal outcomes and explore potential predictors of adverse perinatal outcomes among women with a cfDNA NC. We performed a retrospective cohort study of all women who underwent cfDNA through the perinatal genetics department at a single large tertiary care center from 2011-2016. Women with a reported technical reason for NC and multiple gestations were excluded. Perinatal outcomes were collected for women with NC on cfDNA and reported using descriptive and univariate statistics. The primary outcome was a composite adverse perinatal outcome including spontaneous abortion, stillbirth, neonatal death before discharge, preterm birth, hypertensive disorders of pregnancy, low birth weight, small for gestational age at birth, aneuploidy, major neonatal structural malformation and suspected neonatal syndrome not otherwise specified. Women with an adverse perinatal outcome were compared to those without an adverse outcome and odds ratios (OR) with 95%CI were reported. Logistic regression was used to adjust for maternal BMI. Among 2389 women undergoing cfDNA, 105 (4.4%) had a NC. Of women with a NC, 83 (79.0%) met inclusion criteria. The reason for NC was reported as LFF for 77 (92.77%) women. The frequency of adverse perinatal outcome was 36.0% (n=27). Secondary outcomes are detailed in the table. Maternal age, BMI and pre-existing diabetes did not differ between women with an adverse perinatal outcome and those without (p=0.70, p=0.19 and p=0.52), respectively. The adjusted OR for adverse perinatal outcome among women with a non-technical NC result other than LFF was 10.95 (p=0.032 95% CI 1.24-96.98). There is a high rate of adverse perinatal outcomes among women with a non-technical NC cfDNA result which is further heightened among women with a non-technical reason other than LFF. These findings suggest increased maternal and fetal surveillance is warranted among pregnancies with non-technical cfDNA NC results.