Second trimester uterine arteries pulsatility index is a function of placental pathology and provides insights on stillbirth aetiology: A multicenter matched case-control study.

Introduction: The aim of this study was to investigate the relationships between maternal vascular malperfusions (MVM) and second trimester uterine arteries pulsatility index (UtA-PI) in cases of stillbirth (SB), compared to live-birth (LB) matched controls.

Methods: This was a multicentre, observational, matched case-control study performed at five referral maternity centres over a 4-year period including SB and LB control pregnancies at high-risk for preeclampsia (PE) and/or fetal growth restriction (FGR), matched and stratified for UtA-PI MoM quartiles values of the SB cases. Logistic regression was used to assess the rates of each MVM finding, within each increasing MoM quartile subcategory in SB and matched LB controls.

Results: 82 SB and 82 LB matched high-risk pregnancies were included. Placental hypoplasia, placental infarction, retroplacental hematoma, distal villous hypoplasia and accelerated villous maturation showed a significant correlation with UtA-PI. At univariable analysis, placental infarction and distal villous hypoplasia were more highly associated with the increasing quartile uterine Doppler measurements (odds ratio 2.24 and 2.23, respectively). Logistic regressions showed a significant positive and independent association between rates of retroplacental hematoma or distal villous hypoplasia and stillbirth within corresponding UtA-PI MoM quartiles (odds ratio 5.21 and 2.28, respectively).

Discussion: We are providing evidence for characterization of two major etiological stillbirth categories, characterized by a positive or absent association with UtA-PI impairment and specific histopathological placental MVM lesions. Our results support a strict third trimester follow-up of cases with increased second trimester UtA-PI, in order to improve the reproductive chances of these pregnant patients.