The Stimulation To Induce Mothers Study (STIM)

The investigators propose a parallel group randomized clinical trial of intrapartum nipple stimulation versus exogenous oxytocin infusion for nulliparous women undergoing induction of labor near term. The central hypothesis is that intrapartum nipple stimulation to induce labor increases spontaneous vaginal delivery, improves patient-centered outcomes such as childbirth satisfaction, labor agentry, and pain scores, and reduces adverse neonatal and maternal outcomes in nulliparous women. The investigators will pursue the following specific aims: 1) Assess the effectiveness of intrapartum nipple stimulation on the rate of spontaneous vaginal delivery in nulliparous women (Primary Aim), 2) Determine the effect of intrapartum nipple stimulation on the rate of adverse maternal and neonatal outcomes (Secondary Aim #1), 3) Determine the impact of intrapartum nipple stimulation on patient-centered outcomes (Secondary Aim #2) and 4) In a sub-cohort of women who are enrolled in the trial, to measure the change in oxytocin concentration from baseline to time at which patient achieves a regular contraction pattern, and to measure correlation between salivary and serum oxytocin concentrations in patients undergoing induction of labor via intrapartum nipple stimulation versus continuous exogenous oxytocin infusion. The investigators estimate that randomizing a total of 562 women will provide adequate statistical power to detect meaningful differences in the primary outcome.

Inclusion Criteria:

• Nulliparous
• Gestational age 36 0/7 weeks and greater at enrollment
• Singleton gestation
• Planned to undergo initiation of exogenous oxytocin infusion by their maternity care provider
• Spontaneous rupture of membranes or if membranes intact, modified Bishop score ≥5 and cervix dilated <6 cm within one hour of enrollment
• Ability to give informed consent

Exclusion Criteria:

• Unable to understand English
• Prior use of exogenous oxytocin or attempt at nipple stimulation during the current pregnancy
• Presence of tachysystole (defined as more than 5 contractions in 10 minutes averaged over 30 minutes), recurrent variable or late fetal decelerations, and bradycardia in the prior 30 minutes before enrollment
• Non-vertex presenting fetus at time of enrollment
• Planned for cesarean delivery or contraindication to labor by institutional policy (e.g., placenta previa, vasa previa, active genital herpes infection, previous transmural myomectomy)
• Multi-fetal gestation (e.g., twins, triplets, and higher-order multiples)
• Intrauterine fetal death
• Major fetal anomaly suspected prenatally (defined as a fetal anomaly with anticipated neonatal intensive care unit admission)
• Suspected alloimmunization (given the increased likelihood for anticipated neonatal intensive care unit admission)
• Known severe fetal growth restriction (estimated fetal weight <3rd percentile) or abnormal umbilical artery Doppler studies (given the increased likelihood for anticipated neonatal intensive care unit admission)
• HIV infection (nipple stimulation is not encouraged given the recommendation for these mothers not to breastfeed)
• Participation in another interventional study that influences management of labor and delivery or perinatal morbidity or mortality
• History of mastectomy or other contraindication to use of electronic breast pump
• Known allergic reactions to components of the electronic breast pump or to synthetic oxytocin intravenous solution
• Significantly impaired consciousness or executive function (e.g., intubated or sedated)