The Role of Preterm Placental Calcification in High-Risk Pregnancy as a Predictor of Poor Uteroplacental Blood Flow and Adverse Pregnancy Outcome

This prospective cohort study aims to clarify the role of preterm placental calcification in high-risk (i.e., hypertension, diabetes, placenta previa or severe anemia) pregnant women as a predictor of poor uteroplacental blood flow (absent or reverse end-diastolic velocity [AREDV]) and adverse pregnancy outcome. Monthly ultrasound was performed starting at 28 weeks' gestation to establish the diagnosis of Grade III placental calcification, with measurement of Doppler velocimetry in the umbilical vessels at 32 weeks' gestation. The participants were classified into three groups: Group A (n = 776), a low-risk group without antenatal complication; group B (n = 42), a high-risk group with preterm (28 to 36 weeks) placental calcification; and group C (n = 71), a high-risk control group without preterm (<36 weeks) placental calcification. Analyzed by logistic regression, the risks of AREDV (OR 4.32, 95%CI 1.25 to 14.94), adverse maternal outcome including postpartum hemorrhage (OR 3.98, 95% CI 1.20 to 13.20), placental abruption (OR 4.80, 95% CI 1.19 to 19.35), maternal transfer to intensive care unit (OR 3.83, 95% CI 1.10 to 13.33) and adverse fetal outcome including preterm birth (OR 3.86, 95% CI 1.32 to 11.29), low birth weight (OR 2.99, 95% CI 1.11 to 8.03), low Apgar score (OR 5.14, 95% CI 1.64 to 16.08) and neonatal death (OR 4.52, 95% CI 1.15 to 17.73) were greater in group B compared with group C. In contrast, the risks of AREDV and adverse pregnancy outcome were significantly lower in group A than those in group C, except postpartum hemorrhage (OR 0.53, 95% CI 0.19 to 1.46). We conclude that in high-risk pregnant women, the presence of preterm placental calcification is a predictor of poor uteroplacental flow and adverse pregnancy outcome, requiring closer surveillance for maternal and fetal well-being. This finding helps identify the most dangerous population among high-risk pregnant women.