Am J Obstet Gynecol MFM. 2023 May 9:101012. doi: 10.1016/j.ajogmf.2023.101012. Online ahead of print.
ABSTRACT
BACKGROUND: Some data suggest an association between abnormal fetal fraction on noninvasive prenatal screen and adverse pregnancy outcomes including low birthweight, preeclampsia, and preterm birth in the absence of aneuploidy. These findings suggest that abnormal fetal fraction may be associated with placental pathologic processes in early gestation.
OBJECTIVE: The purpose of this study is to determine the independent association of fetal fraction on genetic noninvasive prenatal screen and histologic placental types.
STUDY DESIGN: This is a retrospective cohort study at a single institution between January 2017 and March 2021 of livebirths ≥ 24 weeks who had noninvasive prenatal screen (NIPS) and placental pathology results available. Results were stratified by trimester of NIPS. Clinical characteristics were compared by quartile of FF using chi square tests. Linear regression was used to model continuous FF as a function of 3 histologic types representing chronic placental injury- chronic inflammation, maternal vascular malperfusion (MVM), and fetal vascular malperfusion. Inverse probability weighting was used to account for selection bias in characteristics of patients with placental pathology examination.
RESULTS: 1,374 patients had NIPS in the first trimester and 262 in the second trimester. Preterm birth and hypertensive disorders of pregnancy were most common in the lowest quartile of FF. Chronic inflammation was associated with a 0.56 percentage point reduction in FF (95% CI: -0.95, -0.16) and MVM was associated with 0.48 percentage point reduction in FF (95% CI: -0.91, -0.04) in adjusted models. The association with MVM was no longer statistically significant after accounting for selection bias in placentas sent for pathologic examination. Second trimester FF was not associated with placental pathology.
CONCLUSION: Chronic inflammation is associated with lower first trimester FF even after accounting for selection bias. Higher fetal fraction in the second trimester was associated with fetal vascular pathology, although this association was no longer statistically significant after inverse probability weighting to account for selection bias. First trimester FF may be a biomarker of adverse outcomes associated with chronic inflammation.
PMID:37169285 | DOI:10.1016/j.ajogmf.2023.101012
