Prolonged labor, often called “failure to progress,” occurs when childbirth takes longer than established clinical guidelines. Medical professionals monitor progression closely to ensure the safety of the birthing parent and the infant. When labor extends beyond specific time limits, it suggests the body is struggling, requiring medical evaluation and potential intervention.
Defining Prolonged Labor Based on Stage
The criteria for diagnosing prolonged labor are divided across the two main stages: cervical change and delivery. The first stage involves cervical dilation and is broken into the latent and active phases, each with specific time limits. A prolonged latent phase is diagnosed when gradual cervical change exceeds 20 hours for a first-time parent or 14 hours for a multiparous parent.
The active phase begins when the cervix is dilated to 6 centimeters and is expected to progress more rapidly. Protraction in the active phase is defined by an abnormally slow rate of cervical dilation, typically less than 1.2 cm per hour for a first-time parent or less than 1.5 cm per hour for a multiparous parent. Active-phase arrest is diagnosed when no change in dilation occurs for four hours despite adequate contractions, or for six hours with oxytocin augmentation and inadequate contractions.
Once the cervix is fully dilated, the second stage begins, focusing on the infant’s descent and delivery. The second stage is considered prolonged if it lasts three hours or longer for a first-time parent, or two hours for a multiparous parent. These timeframes are extended by one hour when epidural anesthesia is used, as it can sometimes slow pushing efforts. Intervention in a prolonged second stage depends on continued fetal descent and a reassuring fetal heart rate pattern.
Underlying Factors That Contribute to Protraction
Protracted labor is categorized using the “3 Ps” framework: Power, Passenger, and Passage. Issues with “Power” relate to the effectiveness of uterine contractions, which may be too weak or infrequent. This condition is termed hypotonic uterine dysfunction, where the force generated by the uterus is insufficient to overcome resistance.
The “Passenger” refers to the infant, and problems include malposition or excessive size. Fetal malposition, such as the occiput posterior presentation, prevents the head from fitting optimally into the pelvis. Macrosomia, or a significantly large infant, can also mechanically obstruct progress.
The final factor, “Passage,” involves the structure of the birthing parent’s pelvis and soft tissues. Cephalopelvic disproportion (CPD) is a diagnosis where the baby’s head is physically too large to pass through the pelvis, creating a mechanical obstruction. Structural limitations or abnormalities in the birth canal can slow or stop the infant’s descent.
Medical Strategies for Management and Augmentation
When prolonged labor is diagnosed, the initial strategy is augmentation, designed to strengthen and regulate contractions. The most common pharmacological method is synthetic oxytocin, given intravenously to increase the frequency and intensity of uterine contractions. This medication is carefully adjusted to achieve an adequate contraction pattern while constantly monitoring the infant’s response.
Another common intervention is an amniotomy, which involves the artificial rupture of the membranes surrounding the fetus. Releasing the amniotic fluid can help the infant’s head descend and press more firmly against the cervix, potentially speeding up dilation. Non-pharmacological techniques, such as changing the parent’s position or using a peanut ball, are also encouraged to optimize pelvic space and encourage fetal descent.
If augmentation strategies fail, or if concerns arise regarding the health of the infant or parent, operative delivery is often necessary. Persistent failure of the cervix to dilate or the fetus to descend, even with medical stimulation, may indicate an underlying mechanical issue requiring a cesarean section. The goal of management is to balance the desire for a vaginal delivery with the need for maternal and fetal safety.
Potential Outcomes of Protracted Labor
Protracted labor carries specific risks for both the birthing parent and the infant, making timely management important. For the parent, the prolonged duration increases the risk of intrauterine infection, such as chorioamnionitis. Maternal exhaustion is also a common consequence, which can impair pushing efforts and increase the likelihood of postpartum complications.
Prolonged labor is also associated with an increased risk of postpartum hemorrhage (PPH), a significant loss of blood after delivery. This risk occurs because the uterus becomes fatigued after many hours of continuous contractions, making it less effective at clamping down after the placenta is delivered. A longer duration of labor, particularly the second stage, also increases the risk of severe perineal lacerations.
For the infant, the main concern is fetal distress, indicated by abnormal heart rate changes due to reduced oxygen supply. Protracted labor can lead to an increased risk of birth trauma, including conditions like shoulder dystocia. Prolonged periods can also result in a lower Apgar score and a higher chance of admission to the neonatal intensive care unit (NICU).