P09.07: Cell‐free fetal DNA as a marker of adverse perinatal outcome

The aim of this study is to determine if early measurement of fetal fraction (FF) of cfDNA is increased in the plasma of women who subsequently develop different abnormal conditions. This is an observational retrospective study of singleton pregnancies that underwent advanced prenatal screening for fetal trisomies through cfDNA, Panorama™ Test (Natera), from May 2013 to May 2018. Miscarriage, pre-eclampsia, preterm delivery, small for gestational age (SGA) (birth weight < 10th centile), macrosomia and gestational diabetes were considered as adverse perinatal outcomes. The measured FF was log10 transformed. Regression analysis was used to examine the association between log10 FF and maternal (maternal age, body mass index -BMI-, parity, conception by reproduction technique, tobacco consume, race) and fetal characteristics (gestational age). The cohort included 2950 pregnancies with a mean maternal age of 36.3 years (range 20-45) that underwent testing at a mean gestational age of 15.2 weeks. The average FF was 11.9% (range 3.1-29.5). High risk, low risk, redraw rate were 0.4%, 99% and 0.4%, respectively. No results were provided in 5 cases (0.2%). There was a significant negative correlation between log10 FF and BMI (r = -0.389, p < 0.001), and with maternal age (r:- 0.068 p < 0.001) but not with other factors. Overall, rates of 1.2% of miscarriage, 1.4% of pre-eclampsia, 5.5% preterm delivery < 37w and 1.3% < 34w, 8.7% of SGA, 3.9% of macrosomia and 9.4% of gestational diabetes were observed. FF was significantly higher in pregnancies that developed SGA, although this difference disappeared when correcting by BMI. For none of other risk groups an association with FF could be established. These preliminary results show that an increased FF might help to predict those patients who will develop fetal growth anomalies, particularly SGA, in the early stages of the pregnancy. Other than SGA and early miscarriage, early determination of FF seems to have a limited use as screening parameter for adverse perinatal outcome in a low-risk population. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.