Effect of Epidural Analgesia During Labor on Force of Maternal Push

There are multiple factors that determine progress of normal vaginal delivery. Frequency, duration and strength of uterine contractions are important for progress throughout labor, and abdominal wall muscle contractions contribute to progress during the final stage. Epidural analgesia helps to alleviate the pain associated with uterine contractions, this however this comes at the expense of prolonging labor by reducing the strength of abdominal wall muscle contractions. The purpose of this prospective study is to quantify how much epidurals decrease the strength of abdominal wall contractions. Intraabdominal pressure will be used as surrogate to strength of abdominal wall contractions, and it will be measured via a foley catheter inserted into the urinary bladder as part of standard procedure for patients receiving labor epidurals. We will compare the change in intraabdominal pressure when patients perform forceful abdominal contractions (valsalva maneuvers) prior to and during epidural analgesia. This will lay the foundation for a future study in which we plan to compare the effects of different epidural analgesia types and concentrations on abdominal wall muscle contractions.