Three volumes. It is the earliest extant specialized book on obstetrics, discussing diseases and treatment prescriptions during pregnancy, parturition, and the postpartum period. An additional volume is appended, containing Zhou Ting's teachings on emergency formulas, Li Shisheng and Guo Jizhong's theories on childbirth with appended prescriptions, and 18 postpartum theories with appended prescriptions. This book is also known as Chan Bao (Treasures of Obstetrics). It was written by Zan Yin during the Dazhong era (847-852) of the Tang Dynasty. This book is the earliest extant specialized monograph on obstetrics in China. It was recorded in the Chongwen Zongmu (Comprehensive Bibliography of the Chongwen Hall) in three volumes. The Song Dynasty edition was lost by the Yuan and Ming periods. Later, the Japanese scholar Funabashi collected over 320 prescriptions from the Yi Wan Lei Ju (Classified Collection of Medical Works), and a printed edition was circulated. The main extant versions include a facsimile of the Song edition from the third year of the Guangxu reign (1877) of the Qing Dynasty. The People's Medical Publishing House published a facsimile in 1955 based on the Northern Song edition from the Guangxu era.

Chan Bao consists of 3 volumes, divided into 52 chapters with 371 prescriptions. The first volume discusses fetal nourishment, fetal protection, dietary contraindications, morning sickness, threatened abortion, fistula disease, vaginal bleeding, edema, abdominal distension and fullness, and difficult delivery. It particularly emphasizes transverse and breech deliveries. The middle and lower volumes discuss the treatment of various obstetric diseases and include 25 chapters on formulas. The appendix records Zhou Ting's Chuan Shou Ji Emergency Formula Theory and Li Shizhong and Guo Jizhong's "Twenty-One Syndromes." Additionally, it includes the "Eighteen Postpartum Theories and Prescriptions," which are renowned obstetric works from before the Song Dynasty and hold significant reference value.