Serum estradiol to testosterone ratio as a novel predictor of severe preeclampsia in the first trimester.

"CONFLICT OF INTEREST Yongmei Shen, Jiasong Cao, Liying Yao, Shanshan Li, Xiaomin Zhao, Wen Li, Zhuo Wei, Lei Zhang, Jianxi Wang, Ying Chang declare that they have no conflict of interest."

"This study was supported by National Natural Science Foundation of China (82001579), Natural Science Foundation of Tianjin (21JCQNJC00040), Tianjin Key Medical Discipline (Specialty) Construction Project (TJWJ2021QN053), Open Fund of Tianjin Central Hospital of Gynecology Obstetrics/Tianjin Key Laboratory of human development and reproductive regulation (2022XH10). All authors contributed to either conceptualization. Software: Yongmei Shen and Jiasong Cao. Resources: Liying Yao. Ultrasonography: Xiaomin Zhao and Lei Zhang. Serum detection: Shanshan Li and Wen Li. Formal analysis: Yongmei Shen and Jianxi Wang. Writing‐original draft preparation: Yongmei Shen. Writing‐review and editing: Jianxi Wang. Supervision: Jiasong Cao and Zhuo Wei. Project administration: Ying Chang and Liying Yao. Funding acquisition: Yongmei Shen and Zhuo Wei. All authors have read and agreed to the published version of the manuscript."