EP17.37: Low fetal fraction of cfDNA and obstetric complications in screening centre Gennet 2019–2022

To assess the association of low fetal fraction (FF) of cfDNA and obstetric complications. cfDNA screening for chromosomal defects was performed in 3048 pregnant women at the GENNET screening centre in the period 2019 - 2022. Tests were collected between 10 and 20 weeks of gestation. Pregnancy complications such as pregnancy-induced hypertension(PIH), pre-eclampsia (PE), small gestation age (SGA), preterm delivery and gestational diabetes mellitus (GDM) were retrospectively evaluated in a group of pregnant women with low FF cfDNA ≤4% and a control group with FF cfDNA >4%. In 47 pregnant women (1.5% of tests), FF ≤4%. Outcome was obtained from 21 pregnant women. The prevalence of PIH, PE, SGA, preterm delivery < 37 weeks and GDM were 25%, 12.5%, 0% and 25%, respectively. The incidence of PIH and GDM was higher in women with low FF compared to the reference group. In our study, we were able to demonstrate the association of low FF with pregnancy complications - PIH and GDM. Due to the small number of cfDNA tests evaluated, further study with larger sample size is needed to test the hypothesis.