Subchorionic Hematoma as an Early Marker of Placental Dysfunction: A Prospective Cohort Study

Purpose: To evaluate whether subchorionic hematoma (SCH) in early pregnancy is associated with a higher frequency of preeclampsia, preterm birth, small for gestational age (SGA) newborns, placental abruption, and other outcomes related to placental dysfunction. Material/Methods: A prospective observational study was conducted from December 2020 to July 2025. A total of 460 pregnant women were analyzed, including 178 with SCH and 282 controls without ultrasound evidence of SCH. The frequencies of preeclampsia, preterm birth, SGA, intrapartum complications, and selected associations with SCH size and location were evaluated. Categorical variables were compared using the chi-square test and Fisher’s exact test. A value of p<0.05 was considered statistically significant. Results: Preeclampsia occurred in 24.2% of women with SCH compared with 7.8% in controls, p=0.001. Preterm birth was observed in 20.2% versus 2.1%, p<0.001. SGA occurred in 37.1% versus 7.1%, p<0.001. Intrapartum complications were more frequent in women with SCH, 11.2% versus 2.8%, p<0.001. Placental abruption accounted for the main difference, 6.7% versus 0.7%, p<0.001. Within the SCH group, a larger hematoma size was significantly associated with preterm birth. Conclusions: SCH in early pregnancy was associated with a higher frequency of preeclampsia, preterm birth, SGA, and placental abruption. These findings suggest that SCH may identify pregnancies with increased risk of placental dysfunction-related outcomes. Due to the observational design, the results should be interpreted as associations rather than evidence of causality.