Highlights
- Individualization of pushing duration is essential: spontaneous delivery probabilities vary drastically based on parity, epidural use, and fetal head position.
- Epidural analgesia is a potent risk factor for persistent occiput posterior (OP) position at delivery (aOR 4.0), significantly reducing the likelihood of spontaneous vaginal birth.
- Active pushing for more than 30 minutes is associated with elevated risks of obstetric anal sphincter injuries (OASI), postpartum hemorrhage (PPH), and adverse neonatal outcomes.
- Delayed pushing policies (passive second stage) can drastically shorten the duration of active expulsive efforts, often to under 15 minutes, without compromising safety.
Background
The management of the second stage of labor—specifically the active pushing phase—has remained a subject of clinical debate for nearly seven decades. In 1955, Emmanuel Friedman established the first widely accepted labor curves, suggesting that the second stage should ideally conclude within two hours for nulliparous women without epidural analgesia. However, contemporary obstetrics has seen significant shifts: the near-ubiquity of epidural analgesia, an older maternal age profile, higher rates of labor induction, and increasing birth weights have rendered the original Friedman curves less applicable to modern practice.
Determining how long a woman should push involves balancing the desire for a spontaneous vaginal delivery against the risks of maternal and neonatal morbidity. Prolonged expulsive efforts are linked to pelvic floor trauma and neonatal hypoxia. Conversely, premature instrumental intervention carries its own set of risks. This review integrates evidence from large-scale retrospective cohorts and prospective studies to provide a data-driven framework for clinical decision-making during the pushing phase.
Key Content
1. Determinants of Spontaneous Delivery Probabilities
The probability of achieving a spontaneous delivery is not uniform but is highly dependent on the intersection of maternal parity and the presence of neuraxial anesthesia. In a landmark retrospective cohort study of 120,218 births (Eide et al., 2026), researchers utilized survival analysis to estimate success rates during the pushing phase. For nulliparous women in the occiput anterior (OA) position without an epidural, the success rate at 120 minutes reached an impressive 98.4%. However, the introduction of an epidural lowered this probability to 84.3%. Interestingly, for this group, extending the pushing phase by an additional 30 minutes increased the probability of success to 90.1%, suggesting that a longer allowance for pushing is beneficial when an epidural is in situ.
For parous women, the timelines are significantly compressed. Those in the OA position without an epidural achieve a 99.0% success rate within just 60 minutes. While an epidural extends this timeframe, success rates still reach 97.4% by 90 minutes. These data suggest that the “benefit” of pushing beyond these specific thresholds—120 to 150 minutes for nulliparas and 60 to 90 minutes for multiparas—diminishes rapidly, particularly in the absence of an epidural.
2. The Challenge of Occiput Posterior (OP) Position
Persistent occiput posterior (OP) position at the time of delivery remains one of the primary obstacles to spontaneous birth. Research indicates that while many fetuses begin labor in the OP position, approximately 80% rotate to OA before delivery. However, epidural analgesia significantly interferes with this rotation. Lieberman et al. (2005) demonstrated that women receiving epidurals were four times more likely to have a fetus in the OP position at delivery (12.9% vs. 3.3%, P=.002). This is likely due to the relaxation of the pelvic floor muscles, which are necessary for the internal rotation of the fetal head.
The impact of OP position on success rates is profound. Among nulliparous women with an epidural and an OP fetus, the probability of spontaneous delivery at 120 minutes of pushing is only 44.9% (Eide et al., 2026). Furthermore, OP position is a confirmed strong risk factor for forceps delivery (OR 5.8), alongside other factors such as birth weight >4000g and maternal age >35 years (Eriksen et al., 2006). For these patients, the benefit of pushing beyond the two-hour mark is marginal, as the persistent malposition often necessitates instrumental or surgical intervention.
3. Active vs. Passive Second Stage Management
Recent evidence suggests that the timing of when a woman begins to push (active phase) relative to when she reaches full cervical dilation (passive phase) significantly influences the duration of expulsive efforts. A study conducted at Besançon University Hospital (2026) evaluated a “delayed pushing” policy, where women could wait up to 3 hours after full dilation before beginning active efforts. Under this protocol, the mean duration of active pushing was remarkably short at 8.8 ± 7.9 minutes. Even after a long passive phase (3 hours), the active pushing duration remained under 15 minutes for the majority of women. This approach supports high rates of spontaneous vaginal birth while potentially minimizing the duration of maximum pelvic floor strain.
4. Maternal and Neonatal Safety Thresholds
Clinicians must weigh the pursuit of spontaneous delivery against the escalating risks of morbidity. Data consistently show that active pushing beyond 30 minutes is a critical inflection point. In all women, pushing longer than 30 minutes is associated with higher rates of obstetric anal sphincter injuries (OASI) and postpartum hemorrhage (PPH) exceeding 1000 ml. From a neonatal perspective, prolonged active pushing correlates with lower Apgar scores (<7 at 5 minutes) and, in parous women, an increased risk of umbilical cord pH <7.0 (Eide et al., 2026). These findings underscore that "pushing to the limit" is not a risk-free endeavor.
Expert Commentary
The synthesis of current evidence suggests a move away from rigid, one-size-fits-all time limits in the second stage of labor. The data from Eide et al. (2026) provide a much-needed contemporary update to the Friedman curves, accounting for the physiological impact of epidurals and fetal rotation. One of the most critical takeaways for clinicians is the synergistic negative effect of epidural analgesia and OP position; when these two factors coexist, the likelihood of a spontaneous delivery drops to less than 50% even after two hours of pushing.
Mechanistically, the interference of epidurals with the pelvic floor’s “guiding” function for fetal rotation explains why malposition is more common in this group. Clinicians should consider that while epidurals allow for longer pushing (due to reduced maternal exhaustion), they also change the biomechanical environment. The Besançon study’s success with delayed pushing further suggests that allowing the fetus to descend passively (laboring down) may be the most effective way to keep the final, strenuous active pushing phase short and safe.
A controversy remains regarding the “individualized limit.” While we now have better probability distributions, the exact moment to transition to instrumental delivery remains a clinical judgment. The evidence of increased OASI and PPH after 30 minutes of pushing suggests that even if a woman *can* eventually deliver spontaneously at 180 minutes, the cost to her pelvic floor and her infant’s metabolic status must be considered.
Conclusion
Contemporary labor management requires an individualized approach to the second stage. For nulliparous women with an epidural and an OA fetus, extending the pushing phase beyond the traditional two hours is evidence-based and often successful. Conversely, for women with a persistent OP position, particularly those with an epidural, the chances of spontaneous success are low, and the risks of maternal-fetal morbidity rise as pushing persists. Future research should focus on the long-term pelvic floor outcomes of different pushing durations and the efficacy of manual rotation of the fetal head to convert OP positions to OA, thereby potentially improving the success rates of spontaneous delivery.
References
- Eide B, Eggebø TM, Dalen I, et al. How Long Should Women Push? The Effect of Fetal Position, Parity, and Epidural Use on Spontaneous Delivery. Am J Obstet Gynecol. 2026-05-08. PMID: 42107846.
- Besançon University Hospital. Active second-stage duration under 15 minutes in spontaneous vaginal deliveries with delayed pushing. Am J Obstet Gynecol. 2026;234(5):1470-1477. PMID: 41421747.
- Lieberman E, Davidson K, Lee-Parritz A, Shearer E. Changes in fetal position during labor and their association with epidural analgesia. Obstet Gynecol. 2005;105(5 Pt 1):974-82. PMID: 15863533.
- Eriksen LM, Nohr EA, Kjaergaard H. Risk factors for forceps delivery in nulliparous patients. Acta Obstet Gynecol Scand. 2006;85(3):298-301. PMID: 16553176.
