The relationship between first-trimester subchorionic hematoma, cervical length, and preterm birth

Area of Science:

• Obstetrics and Gynecology
• Maternal-Fetal Medicine
• Reproductive Health

Background:

• Subchorionic hematoma (SCH) is a common finding in early pregnancy.
• The association between first-trimester SCH and adverse pregnancy outcomes requires further elucidation.

Purpose of the Study:

• To investigate the relationship between sonographically diagnosed first-trimester subchorionic hematoma (SCH) and mid-trimester cervical length.
• To assess the association between first-trimester SCH and the risk of preterm birth, independent of cervical length.

Main Methods:

• A cohort study comparing 512 women with first-trimester SCH to 1024 controls.
• Transvaginal cervical length measurement between 18-22 weeks gestation.
• Multivariable regression analyses to assess independent associations with cervical length and preterm birth.

Main Results:

• First-trimester SCH was significantly associated with shorter cervical length (mean difference -0.09 cm, P = .038).
• Women with SCH had a higher incidence of preterm birth (12.5% vs 7.3%, P = .001).
• SCH remained an independent risk factor for preterm birth even after adjusting for cervical length (aOR 1.58, 95% CI 1.09-2.32).

Conclusions:

• First-trimester subchorionic hematoma is a significant predictor of both reduced cervical length and increased preterm birth risk.
• The findings suggest that factors beyond cervical shortening may contribute to preterm birth in women with SCH.