In the past half century, labor and delivery practice has followed the Friedman curve in the United States. However, the obstetric population and labor management have changed substantially during the same period. Mounting evidence has begun to suggest that the Friedman curve may no longer be appropriate for contemporary labor practice. New, evidence-based definitions of labor protraction and arrest are needed. In addition, our understanding of the reasons behind the rising cesarean section rate was incomplete because detailed information on labor and delivery was lacking at a national level. The primary goals of this observational study were:
The CSL collected detailed information from electronic medical records in 228,562 deliveries from 19 hospitals across the U.S. from 2002 to 2008. The most common reason for cesarean section was elective repeat cesarean delivery due to a previous uterine scar, accounting for approximately one third of all cesarean deliveries. However, investigators also found that one out of three first time mothers was delivered by cesarean section and a high percentage of intrapartum cesarean deliveries were performed too soon before women achieved active labor. These findings mean that preventing cesarean delivery in the first pregnancy will go a long way to decrease the national cesarean delivery rate. In another major study from the CSL, labor patterns were found to be different for individual women. Many parturients did not have a clear pattern of active phase, and more importantly, the active phase of labor may not start until 6 cm of cervical dilation or later. This finding differs from the prevailing concepts established by the Friedman curve which illustrated that the active phase starts before 4 cm dilation. Researchers have also compared the differences in labor patterns using data from the CSL of women who presented in labor for delivery and compared them to women from the Collaborative Perinatal Project, another NIH sponsored study from the late 1950's to early 1960s. Labor patterns were found to be longer now than approximately 50 years ago. Researchers have also examined other factors that may affect labor progression and cesarean delivery, such as induction of labor, maternal obesity, and epidural analgesia for labor pain. Other areas of ongoing research include determining the optimal time for second stage of labor, when pushing begins, and exploring how the sociodemographic changes in the current obstetrical population have affected pregnancy complications, maternal and neonatal morbidity, and implications for clinical management including delivery timing and route. Researchers are exploring how chronic diseases such as hypertension, diabetes and asthma also affect these outcomes. Further work from the CSL study will help shape the future clinical care of pregnant women. See the CSL website for further details: https://csl.nichd.nih.gov/.
Una Grewal, Ph.D., M.P.H. & Katherine Laughon Grantz, M.D., M.S.
All related topics
All related news