Tangdi Lin,1 Wenjia Lou,1 Jung hung Chien,2 Xue Zhang,1 Huanhuan Wei,1 Guorong Fan,1 Lan Zhu3 

1Department of Obstetrics and Gynecology, National Clinical Research Center for Obstetric & Gynecologic Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, People’s Republic of China; 2Department of Health & Rehabilitation Science, College of Allied Health Professions, University of Nebraska Medical Center, Omaha, NE, USA; 3Department of Obstetrics and Gynecology, National Clinical Research Center for Obstetric & Gynecologic Diseases, State Key Laboratory of Common Mechanism Research for Major Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, People’s Republic of China

Correspondence: Lan Zhu, Department of Obstetrics and Gynecology, National Clinical Research Center for Obstetric & Gynecologic Diseases, State Key Laboratory of Common Mechanism Research for Major Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, People’s Republic of China, Email zhu_julie@vip.sina.com

Purpose: This study aims to investigate the differences in pelvic floor dysfunction (PFD) and diastasis recti abdominis (DRA) between primiparous and second-parous females with known risk factors controlled.
Patients and Methods: 49 primiparous and 49 age-matched second-parous postpartum after spontaneous vaginal delivery were included between October and December 2023. Independent variables include weight, height, body mass index (BMI), fetal weight, gestational weight gain (GWG). Main outcome measurements include vaginal resting pressure (VRP) and maximum voluntary contraction pressure (MVCP) indicating pelvic floor muscle strength, the stage of anterior (APOP) and posterior pelvic organ prolapse (PPOP) and inter-recti distance (IRD) indicating DRA. Independent t-test and Chi-square test of independence were used to analyze differences between two groups for continuous and categorical variables, respectively.
Results: No significant differences were found in terms of vaginal pressure measurements between two groups (VRP: t (96) = 0.07, p = 0.942; MVCP: t (96) = 0.40, p = 0.689). Second-parous group showed significantly more severe DRA with larger IRD than primiparous group (t (96) = − 2.405, p = 0.018). No significant association was found between parity and APOP stage (χ2(1) = 2.67, p = 0.102) in this current study; however, second-parous females demonstrated greater PPOP stage than primiparous females (χ2(1) = 5.24, p = 0.022).
Conclusion: Second-parous females at similar age are more likely to experience PPOP than primiparous group after spontaneous vaginal delivery. Greater public attention with plausible actions should be taken for second-parous female group to prevent more severe postpartum pelvic floor dysfunction.

Keywords: pelvic floor dysfunction, postpartum, second-parous females, pelvic floor muscle strength, pelvic organ prolapse, diastasis recti abdominis