Comparison of Low-dose and High-dose Oxytocin Regimens for Labor Augmentation

A Randomized Double Blind Clinical Trial Comparing Oxytocin Low-dose and High-dose Regimens for Labor Augmentation

Oxytocin is a medication that is often used to strengthen contractions to overcome delayed labor progress. The primary aim of this study is to determine whether receiving a higher dose of oxytocin lowers the chance of needing a cesarean section when compared to a lower dose of oxytocin. Other aims include examining the relationship between dose of oxytocin regimen and length of labor, postpartum hemorrhage, intrauterine infection, umbilical cord gas, neonatal Apgar score <5 at 5 minutes, and need for neonatal intensive care.

This randomized double blind clinical trial of consenting nulliparous women in spontaneous labor who require oxytocin for labor augmentation seeks to determine whether use of a high dose oxytocin regimen improves obstetric outcomes when compared with a low dose oxytocin regimen, in a manner that is safe for both mother and neonate. This project will include 1002 women recruited from the obstetrical service at Prentice Women's Hospital. Women will be included if they are at least 36 weeks gestation, have a singleton pregnancy, and have been diagnosed with spontaneous labor or spontaneous rupture of membranes. Women will be exposed to oxytocin for the indication of labor augmentation at the discretion of their obstetric provider. Women will be randomized with equal probability to intervention group using a fixed allocation procedure. To maintain a double blind design, the Prentice Women's Hospital pharmacy will carry out the randomization of oxytocin solutions according to the random assignment so that neither the women or their care providers nor the investigators will know the identity of the intervention assignment. The low-dose oxytocin regimen group will receive a starting oxytocin regimen concentration rate of 2 milliunits/minute that can be increased at increments of 2 milliunits/minute, as per the discretion of their obstetric provider. The high-dose oxytocin regimen group will receive a starting oxytocin regimen concentration rate of 6 milliunits/minute that can be increased at increments of 6 milliunits/minute, as per the discretion of their obstetric provider. Once the women are enrolled, randomized, and in receipt of their assigned interventions, further clinical management will be left to the discretion of each woman's obstetric provider. Prior to discharge from the hospital, baseline demographic and clinical data will be obtained via chart review.

The oxytocin solution will be prepared using 90 units of oxytocin in 500 milliliters of normal saline (sodium chloride 0.9%). The oxytocin infusion will be initiated with a starting oxytocin concentration rate of 6 milliunits/minute (volume rate 2 milliliters/hour) that can be increased at increments of 6 milliunits/minute (volume rate 2 milliliters/hour) every 15-30 minutes until a labor pattern with uterine contractions every 2-3 minutes of moderate to strong intensity is established.

The oxytocin solution will be prepared using 30 units of oxytocin in 500 milliliters of normal saline (sodium chloride 0.9%). The oxytocin infusion will be initiated with a starting oxytocin concentration rate of 2 milliunits/minute (volume rate 2 milliliters/hour) that can be increased at increments of 2 milliunits/minute (volume rate 2 milliliters/hour) every 15-30 minutes until a labor pattern with uterine contractions every 2-3 minutes of moderate to strong intensity is established.

Estimated blood loss greater than 500 milliliters after a vaginal delivery or greater than 1000 milliliters after a cesarean delivery

Fever greater than 100.4 Fahrenheit in the intrapartum period with the initiation of a therapeutic antibiotic regimen in the intrapartum period

Fever greater than 100.4 Fahrenheit in the postpartum period with the initiation of a therapeutic antibiotic regimen in the postpartum period

Umbilical cord arterial blood pH less than 7.0 or base deficit greater than 12 mmol/L; or cord venous blood pH less than 7.0 or base deficit greater than 12 mmol/L when umbilical artery values are not available

Number of participants with neonates with Apgar score of less than 3 at 5 minutes of life. This is using a Apgar scale which ranges from minimum total score of 0 and maximum total score of 10, with higher score representing a better outcome.

Number of Participants Whose Neonates Experience a Composite of Severe Neonatal Morbidity and Perinatal Mortality

Neonatal composite morbidity will be defined as occurrence of any of the following: perinatal death, severe, respiratory distress, major birth injury, encephalopathy, seizure, need for hypothermic treatment, or sepsis

Inclusion Criteria: Able to give informed written consent Age 18-45 years Nulliparous Pregnant with a live singleton gestation that is equal to or greater than 36 weeks Diagnosed with at least 6 regular uterine contractions in an observation period of no more than 60 minutes and at least one of the following: spontaneous rupture of membranes, OR cervix greater than or equal to 3 centimeters dilated OR cervix at least 80% effaced. The participant's attending obstetric physician or midwife has determined that the participant needs administration of oxytocin infusion for labor augmentation. Labor augmentation will be defined as stimulation of uterine contractions when spontaneous contractions have failed to result in progressive cervical dilation of descent of fetus. Exclusion Criteria: Women not meeting the above criteria History of prior cesarean section or uterine surgery Fetus in non-cephalic presentation Participant is undergoing labor induction (i.e. cervical ripening) Non-English speaking

Son M, Roy A, Stetson BT, Grady NT, Vanecko MC, Bond N, Swanson K, Grobman WA, Miller ES, Peaceman AM. High-Dose Compared With Standard-Dose Oxytocin Regimens to Augment Labor in Nulliparous Women: A Randomized Controlled Trial. Obstet Gynecol. 2021 Jun 1;137(6):991-998. doi: 10.1097/AOG.0000000000004399.