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Poster Session 1

Category: Antepartum Fetal Assessment

Poster Session 1

(316) Doppler Progression, Time to Delivery, and Risk of Fetal Demise in Early-Onset Severe FGR

Wednesday, February 11, 2026

10:30 AM - 12:00 PM

Submitting Author and Presenting Author(s)

Noam Pardo, MD, BSc (he/him/his)

MFM Fellow
Sunnybrook Health Sciences Centre
Toronto, Ontario, Canada

Coauthor(s)

JK

John C. Kingdom, MD, MD

Maternal Fetal Medicine Division, Department of Obstetrics and Gynaecology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
Toronto, Ontario, Canada
Nir Melamed, MD

Staff
Sunnybrook Health Sciences Center
Toronto, Ontario, Canada

Objective:
Understanding the natural history of umbilical artery (UA) Doppler in early-onset fetal growth restriction (FGR) is critical for optimal management. However, data on UA Doppler progression and time to delivery are limited by heterogeneous study populations and small sample sizes. Our objective was to characterize the rate of progression of UA Doppler abnormalities, time to delivery, and risk of intrauterine fetal demise (IUFD) in a homogeneous cohort of pregnancies with severe early-onset FGR that ultimately progressed to absent or reversed end-diastolic flow (AREDF) in the UA

Study Design:

This was a retrospective cohort study of patients with a singleton or dichorionic twin pregnancy and severe early-onset FGR that ultimately progressed to AREDF (2014-2024). All cases with genetic or major anatomical anomalies were excluded. UA Doppler findings were categorized as elevated UA-PI ( >95th percentile), intermittent or persistent absent end-diastolic flow (iAEDF or AEDF), and intermittent or persistent reversed end-diastolic flow (iREDF or REDF).

Results:
A total of 287 patients (2,536 ultrasound exams) met the study criteria. There were 16 (5.6%) cases of IUFD. The median (IQR) time to progression was 5 (2-9) days from elevated UA-PI to iAEDF, 4 (2-9) days from iAEDF to AEDF, 5 (2-12) days from AEDF to iREDF, 2 (1-9) days from iREDF to REDF, and 0 (0-3) days from REDF to late DV changes (Fig. 1). The risk of IUFD increased progressively from 1.0% with iAEDF to 14.5% with REDF (Fig. 1). The time to delivery was 7 (3-16) days for elevated UA-PI, 5 (2-12) days for iAEDF, 3 (1-8) days for AEDF, 0 (0-4) days for iREDF, 0 (0-1) days for REDF, 2 (0-11) days for elevated PI in the DV, and 0 (0-4) days for late DV changes (Fig. 2).

Conclusion:

The rates of Doppler progression and time to delivery observed in this homogeneous cohort with severe FGR and AREDF represent a worst-case clinical scenario and can thus inform recommendations on the minimum interval for fetal surveillance. Importantly, the risk of IUFD remains low in the absence of REDF and abnormal ductus venosus Doppler findings.