Once a woman gets fully dilated in labor she has completed her first stage. Once she has her baby she has completed her second stage. The amount of time it takes to complete the second stage is dependent on many factors: the size of the pelvis and the size of the baby, the force of the contractions and the force of the pushing, the direction the baby is going (even a bit off of coming straight down the pelvis slows one down), and whether she has an epidural that is affecting any of the power of pushing. Whether the obstetrician shortens the second stage with a vacuum or forceps or c-section obviously affects that time sequence. And the delivery of the head can be accomplished more easily than the delivery of the shoulders which are a larger diameter than the head. American College of Obstetricians and Gynecologists guidelines to define prolonged second stage for nulliparous women as greater than 3 hours with epidural or greater than 2 hours without epidural. For multiparous women, they defined prolonged second stage as greater than 2 hours with epidural or greater than 1 hour without epidural. . As your birth provider watches you there are clues beyond the stop watch. Specifically the amount of progress, with very little progress from the early pushes there is less hope of achieving a healthy vaginal birth.
S. Katherine Laughon, MD, Investigator, Epidemiology Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, Maryland, and colleagues published the results of their labor review study in the June issue of Obstetrics & Gynecology, showing that beyond 2 hours there are increased risks for both the mother and the child. They noted that labors are longer in these past few years than they were in the past.
The investigators reviewed electronic medical record data from 2002 to 2008, using a retrospective cohort from 19 hospitals at 12 US clinical centers. The researchers included 43,810 first time moms and 59,605 women who had had a child before who were at least 36 or more weeks of gestation, with head down (vertex) presentation and 10 cm of cervical dilation in the analysis, meaning they specifically studied the second stage.. Longer labors are common, about 10-15% in women who have epidurals, and about 3-5% of women who do not, and yet most women, about 80-90% will still accomplish the vaginal delivery even if they are moving slowly compared to normal standards.
The risks for mom of having that long second stage are infection and more significant tears to the pelvic floor, with baby also infection rates, and rates of having low oxygen increase, although they found no severe complications of that hypoxia, it is critical to note there was no increased rates of perinatal death. Experienced obstetricians can diagnose this lack of progress prior to two hours, and be able to predict whether normal or slowed progress is occurring, and whether it is healthy for you to keep pushing or have your obstetrician intervene.