Exploring the Passive Second Stage of Labour and Related Perinatal Outcomes in a Physiological Cohort

Background: The passive second stage of labor has been increasingly recognized as a normal phase of labor. However, it remains poorly studied, especially in healthy women. This study aims to assess the passive phase in healthy laboring women and maternal and neonatal outcomes. Methods: A retrospective cross-sectional study on women who gave birth in an Italian University maternity center between 2019 and 2023. Only healthy laboring women without epidural analgesia or intrapartum interventions were included. Data were extracted from electronic records and analyzed overall and by parity. Results: A passive second stage was identified in 466 out of 2810 eligible women (16.6%), with a median duration of 30 min. The passive phase occurred more frequently in nulliparous women (63.9%; p < 0.001) and was associated with more advanced cervical dilatation at partograph initiation (p < 0.001) and longer second-stage duration (p < 0.001), even when stratified by parity. Analysis stratified by parity showed higher rates of episiotomy (p = 0.02) and lithotomy position (p = 0.013) among nulliparas, and of neonatal macrosomia (p = 0.001) and NICU admissions (p = 0.009) among multiparas with a passive second stage. Mode of birth did not differ in either group. Discussion: The passive second stage occurred in a minority of healthy laboring women and may be underdiagnosed due to inconsistent definitions and reliance solely on vaginal examinations. Recognizing and accurately documenting this phase may contribute to a more precise description of physiological labor progression, without implying causal effects on maternal or neonatal outcomes.