A New Era in Intrapartum Care: Moving Beyond the Friedman Curve

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As health care providers, we constantly dance between the process of recognizing and supporting normal health and the need to identify and treat signs of disease or disorder. Being “on top of your game” requires maintaining equipoise on this mental balance beam. When new evidence changes the definition of what is normal or abnormal, it is both uncomfortable and anxiety-provoking because integrating new clinical paradigms requires a conscious shift in our carefully constructed equilibrium.

I felt this anxiety quite keenly when I recognized that induction of labor at 41 weeks' gestation is safer than expectant management.1 I had always believed that nature knew best, and I encouraged women to wait until 42 weeks before considering induction. When I learned that the cost-benefit analysis had changed, I had to alter my practice because I want to give laboring women the best care possible. In the case of induction of labor, this was probably a more difficult shift for me to make than it was for many of my physician colleagues. Put simply, physicians are trained to identify abnormal situations and fix them, whereas I am an expert in facilitating and supporting normal life processes. Giving up a definition of what is normal is a bigger change than the smaller shift of determining when induction of labor is safest.

In the case of the Friedman Curve, midwives may have an easier time accepting new evidence and reconceptualizing the course of labor. Midwifery research has played an important role in the body of work that identified the failings of the Friedman Curve,2-4 and midwives may find themselves leading the changes in practice that are necessary. Understanding the problem is the first step in devising a solution.

Dystocia accounts for approximately half of the primary cesareans performed in the United States, making it the leading indication for this surgery.5 Dystocia also accounts for the most variability in institutional cesarean rates,6 which suggests that there are no established best practices or evidence-based guidelines that can help us decrease the number of cesareans performed for this indication. However, the problem causing the current epidemic of dystocia has been identified. It turns out that the Friedman Curve we have used for so long to determine the outer limits of what is normal for duration of the stages of labor is incorrect.

Dr. Emanuel Friedman first published the simple plot of time versus dilation in 1955.7 Friedman recorded the progress of 500 nulligravid women to determine the mean, median, range, and standard deviation of the first stage of labor by plotting these labors on a simple graph using the x-axis for cervical dilation and the y-axis for time. He divided the resulting sigmoid curve into the latent, active, and transition phases “for purposes of mathematical simplification.”7 Unfortunately, the labors that informed the Friedman graph are not an accurate reflection of spontaneous, unmedicated labor progress.4,8-10 In fact, they were probably not even an accurate depiction of labor in 1955, an especially compelling piece of data that supports discarding the Friedman partogram.5

So, what do we know about labor progress? First, the latent phase lasts longer than previously thought. Zhang et al5 used a repeat measures analysis that determined the time interval between each centimeter of cervical dilation instead of the simple overall average used by Dr. Friedman.7 The change from latent to active labor in a nulliparous woman may not occur until her cervix is 5 to 6 cm dilated. Furthermore, rates of dilation for nulliparous women in the active phase are not linear as Friedman found. Dilation can take up to 2.6 hours to progress from 5 to 6 cm, but the outer limit of time to change from 8 to 9 cm is closer to 1.2 hours. Although labor progressively accelerates, there is significant interindividual variability. Before 7 cm of cervical dilation, it is not uncommon for nulliparous women to experience more than 2 hours without progressive cervical dilation.9 Racial and ethnic differences exist but have yet to be sufficiently defined.2

Discarding the Friedman Curve and delaying use of the diagnosis of dystocia will be the 2 most effective steps in lowering the primary cesarean rate. So how do we get there? Neal and Lowe11 have recently developed a partogram that takes into account the recent, more sophisticated analyses of normal labor progress. Clinical studies that test the validity of this partogram are pending. In the meantime, for many women, patience and delaying the administration of oxytocin for augmentation can be justified now.

Additional care practices will be needed when women are allowed to labor longer. All of the support techniques that are an integral component of midwifery, nursing, and doula care will be required. Perhaps more importantly, we need to bring women along with us on this journey of change. Patient education that is effective, culturally sensitive, and written to accommodate the health literacy of the recipient is not easy to compose. This issue of the Journal of Midwifery & Women's Health includes a Share With Women patient education handout that is written for pregnant women as they assess their choices for intrapartum care. This handout will not replace face-to-face time during prenatal visits, but it will introduce the topics that women and their providers will want to discuss as a counterpoint to the misinformation that abounds in the media many women are exposed to.

Although the era of the Friedman Curve is over, health care practices do not usually change quickly. It is easier to stay poised on the balance beam that separates normal from abnormal by relying on tradition-based practice rather than trying to incorporate evidence-based practice. However, this change is not going to be too difficult for midwives. We have always known there are significant differences between women in the progress of normal labor, and we have the tools needed to help them through the process. Now we also have the scientific evidence that justifies patience when caring for women during their labors.

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