Adverse perinatal outcomes are more frequent in pregnancies with a low fetal fraction result on noninvasive prenatal testing

Abstract

Objective: This study aimed to assess risk of an adverse perinatal outcome for women with a low fetal fraction (LFF) result on noninvasive prenatal testing (NIPT). Study Design: A retrospective cohort study whereby women with an LFF result were compared with women who had a sufficient fetal fraction (SFF) result on NIPT. Inclusion criteria were singleton pregnancies with quantification of fetal fraction and pregnancy outcome information. Primary outcome was a composite of any of the following: miscarriage, fetal demise, neonatal death, preterm birth, pregnancy-associated hypertensive disorder, placental abruption, and low birth weight. Results: Three hundred forty-eight (94%) women had an SFF result, and 22 (6%) women had an LFF result. The mean gestational age at the time of NIPT was comparable for both groups. Women with an LFF result were more likely to be African American (86% vs 52%; p=0.007) and have a higher body mass index (BMI) (mean BMI=37kg/m2 vs BMI=29kg/m2; p≤0.001) than women with an SFF result. The composite outcome was significantly more common in the LFF group (59.1% vs 29%; p=0.003). After adjusting for race and BMI, LFF remained independently associated with adverse perinatal outcome with adjusted odds ratio=2.5 (95% confidence interval 1.01-6.2; p=0.049). Conclusions: Women with an LFF result have an increased likelihood of an adverse pregnancy outcome.