Poster Session 1
Katelyn J. Rittenhouse, MD
Global Women's Health Fellow
University of North Carolina - Chapel Hill
Chapel Hill, North Carolina, United States
Margaret P. Kasaro, MBBCH, MSc
Country Director
UNC Lusaka
UNC Zambia, Lusaka, Zambia
Yuri Sebastião, PhD
Research Assistant Professor
University of North Carolina at Chapel Hill
Chapel Hill, North Carolina, United States
Elizabeth M. Stringer, MD, MSc
Professor of Maternal Fetal Medicine
University of North Carolina at Chapel Hill
Chapel Hill, North Carolina, United States
Bellington Vwalika, MBBCH, MSc
Professor of Obstetrics & Gynecology
University Teaching Hospital
Lusaka, Lusaka, Zambia
Jeffrey S.A. Stringer, MD
Professor of Obstetrics & Gynecology
University of North Carolina at Chapel Hill
Chapel Hill, North Carolina, United States
We sought to estimate the association between abnormal 3rd trimester UAD and stillbirth in an unselected, well-characterized Zambian cohort.
Study Design:
The Zambian Prematurity Prevention Study (ZAPPS) is a prospective antenatal cohort in Lusaka with continuous enrollment since 2015. Since 3/2020, UAD were routinely obtained during 3rd trimester ultrasound. FGR was defined as an estimated fetal weight (EFW) < 10%ile. Abnormal UAD was defined as 1) reversed or absent end diastolic flow (EDF) or 2) systolic/diastolic (S/D) ratio >95%ile for gestational age. FGR and S/D ratio were estimated using INTERGROWTH-21st standards. The primary outcome was stillbirth, defined as fetal death >20wks gestation. Using marginal standardization, we estimated crude and adjusted risk of stillbirth among singleton gestations. We also estimated risk of NICU admission and 5 minute APGAR < 7.
Results:
Between 9/2020-12/2022, 988 singletons were enrolled in ZAPPS with a 3rd trimester growth ultrasound performed (range: 31-34wks). Delivery outcome was available on 978 pregnancies (99%) with 11 (1%) cases of stillbirth. During 3rd trimester ultrasound, 92 (9%) pregnancies were diagnosed with FGR and 77 (8%) had abnormal UAD (absent EDF: 32; S/D >95%ile: 45). Both FGR (ARR: 4.1; 95%CI: 1.1,15.1) and abnormal UAD (ARR: 5.5; 95%CI: 1.6, 18.7) were associated with increased risk of stillbirth in analyses adjusted for advanced maternal age and hypertension. The association between abnormal UAD and stillbirth was present even among normally grown fetuses (ARR: 6.6; 95%CI: 1.6,27.3). Abnormal UAD were also associated with NICU admission (RR: 2.0 95%CI 1.1 3.4) and 5 minute APGAR < 7 (RR: 3.1 95%CI: 1.3,7.6).
Conclusion: In this well characterized urban African cohort, abnormal UAD was common, only rarely comorbid with FGR, and independently associated with stillbirth. Further research is needed to understand the role of screening for abnormal UAD in this population.
