Am J Perinatol 2017; 34(01): 38-43
DOI: 10.1055/s-0036-1584143
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Intravenous Acetaminophen versus Morphine for Analgesia in Labor: A Randomized Trial

Nana-Ama E. Ankumah
1  Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas Health Science Center at Houston, Houston, Texas
,
Marissa Tsao
1  Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas Health Science Center at Houston, Houston, Texas
,
Maria Hutchinson
1  Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas Health Science Center at Houston, Houston, Texas
,
Claudia Pedroza
2  Center for Clinical Research and Evidence-Based Medicine, Department of Pediatrics, University of Texas Health Science Center at Houston, Houston, Texas
,
Jaideep Mehta
3  Department of Anesthesiology, University of Texas Health Science Center at Houston, Houston, Texas
,
Baha M. Sibai
1  Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas Health Science Center at Houston, Houston, Texas
,
Suneet P. Chauhan
1  Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas Health Science Center at Houston, Houston, Texas
,
Sean C. Blackwell
1  Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas Health Science Center at Houston, Houston, Texas
,
Jerrie S. Refuerzo
1  Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas Health Science Center at Houston, Houston, Texas
› Author Affiliations
Further Information

Publication History

11 March 2016

31 March 2016

Publication Date:
16 May 2016 (online)

Abstract

Objective To compare the effectiveness of intravenous acetaminophen with that of morphine in reducing pain in the first stage of labor.

Methods An open-label, randomized controlled trial of women ≥ 34 weeks gestation in the first stage of labor, assigned to either intravenous acetaminophen or morphine. The primary outcome was improved analgesia measured by difference of visual analog scale (VAS) score at 120 minutes from baseline. Secondary outcomes were request for rescue analgesia, maternal side effects, and fetal heart rate changes. Statistical analyses performed were chi-square, Student's t-test, and Kaplan-Meier survival analysis.

Results Of 40 women randomized, 18 received acetaminophen (2 did not receive study drug), and 20 received morphine. Because of difficulties in recruitment, the sample size of 88 was not achieved. The primary outcome was similar between groups (p = 0.53). Within 120 minutes of initial treatment, more women receiving intravenous acetaminophen required rescue analgesia (acetaminophen: 52.9% vs. morphine: 17.6%, p < 0.01). Maternal and fetal side effects were similar between groups.

Conclusion There was no difference in VAS scores between groups. However, as half of women receiving intravenous acetaminophen required rescue analgesia within 120 minutes of treatment, intravenous acetaminophen may be less effective for analgesia in early labor compared with intravenous morphine.

Presented as an oral presentation at the Society for Maternal-Fetal Medicine 36th Annual Meeting, February 1–6, 2016, Atlanta, Georgia