Oxytocin Administration for Cesarean Delivery
Hormonal processes of childbearing are essential to pregnancy, labor, birth, breastfeeding and the maternal–child attachment.1 Hormone release in both the mother and the baby is coordinated to optimize outcomes, such as maternal and fetal readiness for labor.1 Oxytocin is a hormone that is produced naturally by the body, but also administered to induce labor that may not have started on its own2 or to prevent postpartum blood loss.3 To provide the best care to their parturient patients, anesthesia providers should be familiar with the uses of oxytocin as well as protocols for oxytocin in Cesarean delivery.4
Prelabor preparation in the maternal body involves many complex hormonal and physiological changes.1 These changes, which occur in the weeks, days and hours before the onset of labor in humans and animals, include rising estrogen levels, activating the uterus for efficient labor; increases in oxytocin and prostaglandin activity, causing cervical ripening; increased inflammation, which activates the cervix and uterus; increased uterine oxytocin receptors, allowing for effective contractions during labor and reduced bleeding after birth; increased central nervous system (CNS) receptors for beta-endorphins, contributing to endogenous analgesia in labor; and elevations in mammary and CNS oxytocin and prolactin receptors, which promote breastfeeding and maternal-infant attachment after birth.1 Similarly, changes in hormones and neurotransmitters affect the baby’s adaptations for labor as well.1 In some situations, such as scheduled birth, endogenous hormonal activities do not align with external needs. In these cases, clinicians will administer exogenous hormones to encourage certain processes. Once the cervix has been softened using prostaglandins, a health professional will provide a synthetic version of oxytocin (known as Pitocin) to cause uterine contraction and thus induce labor.5 Oxytocin is more effective at speeding up labor that has already begun than it is at beginning the labor process.5 When epidural analgesia is used during vaginal birth, the resulting reduction in maternal oxytocin may require the clinician to administer exogenous oxytocin to compensate.1 Also, clinicians commonly administer oxytocin after both vaginal and operative delivery to initiate and maintain adequate uterine contractility, thus minimizing blood loss and preventing postpartum hemorrhage.3 Evidently, oxytocin and various other hormones are crucial to efficient labor, and may be administered by clinicians to provoke certain essential processes. Future research is needed to assess the long-term effects of exogenous oxytocin exposure during labor and delivery.6
Anesthesia providers are highly involved in Cesarean sections, and one of their many roles can involve oxytocin administration. Because Cesarean section is fetal birth through incisions in the abdominal wall and uterine wall, it does not involve the same endogenous hormone releases as does vaginal birth.7 Thus, oxytocin infusion at Cesarean section may help maintain uterine contractility throughout the procedure and immediately postpartum, when most hemorrhage (blood loss) occurs.7 The protocols surrounding oxytocin administration for Cesarean section are complicated and must be followed precisely.4 However, there remains a lack of consensus among anesthesiology practitioners regarding optimal dose and mode of administration.8 For example, Terblanche et al.’s review showed no conclusion for or against the effectiveness of 5IU oxytocin versus a lower dose for combatting postpartum blood loss.8 However, Balki et al. found that women requiring Cesarean delivery for labor arrest required approximately 3IU of intravenous oxytocin to achieve effective uterine contraction after delivery.9 Kovacheva et al. found that when compared to women receiving continuous infusions of oxytocin, women who received a low-dose bolus of 3IU oxytocin achieved the same adequate uterine tone while using less oxytocin.10 On the other hand, high doses of oxytocin can cause cardiovascular issues or desensitization of oxytocin receptors.11 Some researchers show that timing may be an important factor in oxytocin infusion. Bhattacharya et al. found that in elective Cesarean delivery patients, bolus oxytocin of 3IU over 15 seconds and infusion of oxytocin at 3IU over five minutes had comparable uterotonic effects, but the bolus administration resulted in significantly more cardiovascular events.3 Additionally, Foley et al.’s retrospective chart review found that pre-Cesarean exposure to oxytocin led patients to require a high postpartum oxytocin infusion rate more often than patients who were not exposed.12 Clinicians have yet to determine the optimal dose and timing of oxytocin doses in Cesarean section.11
Anesthesia providers often care for parturient patients who are experiencing various hormonal changes. Sometimes, vaginal or Cesarean delivery requires exogenous oxytocin to induce labor or prevent postpartum blood loss. Future studies should evaluate the optimal dose of oxytocin doses, the most effective mode of administration and the possible long-term implications of oxytocin administration during Cesarean delivery.
1.Buckley SJ. Executive Summary of Hormonal Physiology of Childbearing: Evidence and Implications for Women, Babies, and Maternity Care. The Journal of Perinatal Education. 2015;24(3):145–153.
2.Hormone Health Network. What is Oxytocin? Glands & Hormones A–Z November 2018; https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/oxytocin.
3.Bhattacharya S, Ghosh S, Ray D, Mallik S, Laha A. Oxytocin administration during cesarean delivery: Randomized controlled trial to compare intravenous bolus with intravenous infusion regimen. Journal of Anaesthesiology, Clinical Pharmacology. 2013;29(1):32–35.
4.Balki M, Tsen L. Oxytocin protocols for Cesarean delivery. International Anesthesiology Clinics. 2014;52(2):48–66.
5.Mayo Clinic. Labor induction. Tests & Procedures September 11, 2017; https://www.mayoclinic.org/tests-procedures/labor-induction/about/pac-20385141.
6.Erickson EN, Emeis CL. Breastfeeding Outcomes After Oxytocin Use During Childbirth: An Integrative Review. Journal of Midwifery & Women’s Health. 2017;62(4):397–417.
7.Abbas AM. Oxytocin Administration During Cesarean Section. ClinicalTrials.gov: U.S. National Library of Medicine; April 23, 2018.
8.Terblanche NCS, Picone DS, Otahal P, Sharman JE. Paucity of evidence for the effectiveness of prophylactic low-dose oxytocin protocols (<5 IU) compared with 5 IU in women undergoing elective caesarean section: A systematic review of randomised controlled trials. European Journal of Anaesthesiology. 2018;35(12):987–989.
9.Balki M, Ronayne M, Davies S, et al. Minimum Oxytocin Dose Requirement After Cesarean Delivery for Labor Arrest. Obstetrics & Gynecology. 2006;107(1):45–50.
10.Kovacheva VP, Soens MA, Tsen LC. A Randomized, Double-blinded Trial of a “Rule of Threes” Algorithm versus Continuous Infusion of Oxytocin during Elective Cesarean Delivery. Anesthesiology: The Journal of the American Society of Anesthesiologists. 2015;123(1):92–100.
11.Yamaguchi ET, Siaulys MM, Torres MLA. Oxytocin in cesarean-sections. What’s new? Brazilian Journal of Anesthesiology (English Edition). 2016;66(4):402–407.
12.Foley A, Gunter A, Nunes KJ, Shahul S, Scavone BM. Patients Undergoing Cesarean Delivery After Exposure to Oxytocin During Labor Require Higher Postpartum Oxytocin Doses. Anesthesia and Analgesia. 2018;126(3):920–924.