Oxytocin Dosage to Decrease Induction Duration

Phase 4

Completed

Conditions: Obesity
Labor, Induced
Oxytocin

Interventions: Drug: Oxytocin

Registration Number: NCT03140488

Lead Sponsor: University of Arizona

Brief Summary: This is a randomized controlled trial in which women are allocated either 'high dose' or 'low dose' oxytocin infusions for induction of labour. The randomization is stratified by maternal body mass index.

Detailed Description: Obesity is considered a major public health concerns and increases the risk of many comorbid medical conditions. Obesity in pregnancy places women at higher risk of obstetrical complications during pregnancy, delivery and postpartum. In particular, obese pregnant women have more difficulty going into labor, a longer labor course, and even with pharmacologic treatment, have a higher chance of requiring cesarean delivery.

When pregnant women need help going into labor, they commonly receive a medication called Pitocin on the labor and delivery floor. Pitocin is the brand name and is a synthetic analog to the naturally produced oxytocin, a hormone secreted by mother when they naturally go into labor. This medication has been used widely around the world. There is emerging evidence that obese women need more oxytocin to go into labor compared to their lean cohorts. There are many studies to support the use of different oxytocin dosage protocols (both high and low dose infusion increments). Despite these evidences, a low dose oxytocin regimen is universally used in the United States, regardless of patient characteristics.

This study is a double blinded randomized controlled trial. Both lean and obese cohorts will be recruited for the study. The investigators will randomly place both cohorts into the low or the high dose oxytocin regimen treatment group. The investigators, patients and providers will be blinded and will not know the specific assignments. The purpose of this study is to evaluate the effect of high dose oxytocin in the obese cohort. The hypothesis is that obese patient will have shorter time to delivery with the high dose oxytocin regimen without incurring any additional risks or adverse outcomes.

Recruitment & Eligibility

Status: COMPLETED

Sex: Female

Target Recruitment: 140

Inclusion Criteria

Singleton pregnancy ≥ 37 weeks gestation
Patient presented for induction of labor who is determined to be a candidate for oxytocin
Cephalic presentation
Reassuring fetal health assessment (no abnormal findings in fetal assessment, see below)
Meeting one of the following BMI category:

Obese group: BMI ≥30 at <20 weeks of pregnancy, or BMI ≥35 at a term gestation of pregnancy Lean group: BMI ≤25 at <20 weeks of pregnancy, or BMI ≤28 at a term gestation of pregnancy

Exclusion Criteria

Non-reassuring fetal assessment at the time of recruitment
Previous cervical ripening agents (cytotec, cervidil, cervical Foley Balloon)
<18 years of age
Prisoners
Any patients contraindicated for vaginal delivery
Multiple gestations
History of previous cesarean delivery
Patients with history of significant cardiac disease
Fetal demise
Estimated fetal weight greater than 4500 grams in diabetic and 5000 grams in non-diabetic mother
Ruptured membranes
Spontaneous labor (latent or active phase)
Augmentation of labor (latent or active phase)

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Lean-Intervention	Oxytocin	2) Intervention group: Lean cohort: BMI ≤25, at \<20 weeks gestation or BMI ≤28 at a term gestation, high dose oxytocin protocol High dose oxytocin regimen (endorsed by American College of Obstetricians and Gynecologists): 90 units in 500cc 0.9% normal saline bag (180 milliunit/cc). Starting rate would be 6 milliunit/minute, or 2cc/hour. The medication will be increased by 6 milliunit/minute = 2cc/hr every 30 minutes until adequacy of contraction or cervical change. At 60 milliunit/minute = 20cc/hr, provider will assess patient for eligibility to continue to increase oxytocin dosage.
Obese-Intervention	Oxytocin	4) Intervention group: Obese cohort: BMI ≥30, at \<20 weeks gestation or BMI ≥35 at a term gestation, high dose oxytocin protocol High dose oxytocin regimen (endorsed by American College of Obstetricians and Gynecologists): 90 units in 500cc 0.9% normal saline bag (180 milliunit/cc). Starting rate would be 6 milliunit/minute, or 2cc/hour. The medication will be increased by 6 milliunit/minute = 2cc/hr every 30 minutes until adequacy of contraction or cervical change. At 60 milliunit/minute = 20cc/hr, provider will assess patient for eligibility to continue to increase oxytocin dosage.
Lean-Control	Oxytocin	1) Control group: Lean cohort: BMI ≤25, at \<20 weeks gestation or BMI ≤28 at a term gestation, low dose oxytocin protocol Low dose oxytocin regimen (the standard at Banner University Labor and Delivery, as well as across the United States): 30 units in 500cc 0.9% normal saline bag (60 milliunit/cc). Starting rate would be 2 milliunit/minute, or 2cc/hour. The medication will be increased by 2 milliunit/minute = 2cc/hr every 30 minutes until adequacy of contraction or cervical change. At 20 milliunit/minute = 20cc/hr, provider will assess patient for eligibility to continue to increase oxytocin dosage.
Obese-Control	Oxytocin	3) Control group: Obese cohort: BMI ≥30, at \<20 weeks gestation or BMI ≥35 at a term gestation, low dose oxytocin protocol Low dose oxytocin regimen (the standard at Banner University Labor and Delivery, as well as across the United States): 30 units in 500cc 0.9% normal saline bag (60 milliunit/cc). Starting rate would be 2 milliunit/minute, or 2cc/hour. The medication will be increased by 2 milliunit/minute = 2cc/hr every 30 minutes until adequacy of contraction or cervical change. At 20 milliunit/minute = 20cc/hr, provider will assess patient for eligibility to continue to increase oxytocin dosage.

Primary Outcome Measures

Name	Time	Method
Length of Time to Delivery	Start of induction to Delivery	Number of minutes from induction of labor with oxytocin infusion to delivery of infant, no maximum amount of time specified.

Secondary Outcome Measures

Name	Time	Method
Number of Participants With Terbutaline Use	Start of induction to Delivery	If terbutaline was injected during labor to decrease number or strength of contraction
Rate of Cesarean Delivery	Start of induction to Delivery	total number of patients who undergo cesarean delivery
Rate of Cesarean Delivery for Labor Arrest	Start of induction to Delivery	Number of patients who undergo cesarean delivery due to labor arrest/ failed induction
Maximum Oxytocin Infusion Rate	Start of induction to Delivery	rate measured in milliunits/minute during induction of labour, no time limit applied.
Maternal Blood Loss	At delivery	Blood loss in milliliters
Number of Neonates With Apgar Score <7	5 minutes after birth	5 minute Apgar Score \<7 \*Apgar is an acronym for which each criterion is given a minimum of 0 and maximum of 2 points: Appearance (skin color), Pulse (heart rate), Grimace (reflex irritability), Activity (muscle tone), Respiration