Study design and population
The prospective observational study was conducted between January 2018 and June 2021 in the department of Obstetrics from Guangzhou Women and Children’s Medical Care Center, China. Singleton pregnancies from 20-36+6 gestational weeks were enrolled when maternal blood pressure exceeded a pre-defined threshold (SBP≥140mmHg and/or DBP≥90mmHg), or when primary chronic hypertension is present regardless of medication intervention. Participants received oral and written information to donate the surplus aliquots of serum samples during prenatal care for scientific research before they gave written consent. The study was approved by Institutional Ethics Committee of the Guangzhou Women and Children’s Medical Center (Reference number: 2017022008).