Using the Peanut Exercise Ball to Reduce Cesarean Section Rates: A Randomized Controlled Trial

This study is designed as a prospective, randomized controlled trial that will compare the use of the peanut exercise ball in laboring patients compared with no use of the exercise ball. The investigators plan to include all pregnant women over the age of 18 who present to VCU Labor and Delivery in labor or for induction of labor with a fetus in cephalic presentation. They will have the peanut shaped exercise ball placed between the maternal legs in either the supine or upright position during labor. The peanut ball can be seen at this link, which is similar to the ball the investigators use on Labor and Delivery (http://www.amazon.com/Isokinetics-Inc-Brand-Peanut-Ball/dp/B0026N2JWG). We use various sizes of this durable, non-latex exercise ball. There is a small size (for women ,5'3" that is 40inches), medium size for women 5'3" to 5'"7 (50inches) and a large for women >5'7" (60inches). The length of time using the peanut ball will be quantified by charting in OB TraceVue software (which is currently standard practice with peanut ball use).

Each patient will be assigned a number in order starting at 1. Each patient will then be randomized using a block randomization scheme with pre-assigned envelopes in the labor and delivery team room starting at number 1. Each participant will have an envelope pulled in order of their number assignment when admitted to labor and delivery and consent obtained.

Exclusion criteria for this study include women with multifetal gestations, fetus in breech or transverse position, musculoskeletal abnormalities in the mother which might preclude them from proper positioning on the peanut ball.

This study is a prospective, two-armed randomized controlled trial (RCT) with interim analyses planned after 50% and 75% of the patients have completed the study. Using nTerim 2.0, 2000 total subjects (1000 per group) will be needed to have a study powered at 80% to detect a difference in the C-section rate if the treatment and control groups have C-section rates of 11.25% and 15%, respectively, using a one-sided test at the 0.05 level. The primary outcome will be the observed incidence of cesarean section delivery in the two populations of randomized, laboring women.

Bayesian stopping rules, for expected success and futility, are to be added to this study. Bayesian stopping rules have advantages over other traditional types of interim analyses. Specifically, they can be used for Bayesian or frequentist (e.g. traditional) trial designs without requiring the statistical analysis or study design to be altered. Additionally, the study is not penalized for additional 'looks' at the data, as is the case in traditional interim analyses. A drawback of this strategy is that the methods used to analyze the data (e.g. frequentist and Bayesian) have different interpretations and may not come to the same conclusion.