CC BY-NC-ND 4.0 · AJP Rep 2019; 09(02): e177-e184
DOI: 10.1055/s-0039-1692196
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Oxytocin and Oxytocinase in the Obese and Nonobese Parturients during Induction and Augmentation of Labor

Annemaria De Tina
1  Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
2  Department of Anesthesiology, McMaster University, Hamilton, Ontario, Canada
,
Jeremy Juang
1  Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
3  Department of Anesthesiology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
,
Thomas F. McElrath
4  Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
,
Jack D. Baty
5  Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri
,
6  Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri
› Author Affiliations
Further Information

Publication History

27 January 2019

12 April 2019

Publication Date:
29 May 2019 (online)

  

Abstract

Objective To investigate differences in oxytocin (OXT) biodistribution between nonobese and obese parturients during labor.

Study Design Patients with body mass index (BMI) of either ≥ 18 ≤ 24.9 kg/m2 (“nonobese”) or ≥ 30 kg/m2 (“obese”) undergoing elective induction of labor were included (N = 25 each). Blood samples were collected at baseline (T0), and 20 minutes after maximal OXT augmentation or adequate uterine contractions (T1) for OXT and oxytocinase assays. A mixed-model repeated-measures analysis of variance was used to test for group versus time interaction and analysis of covariance to detect a difference in OXT level at T1. Data presented as mean ± standard deviation or median (interquartile range), with p < 0.05 considered significant.

Results The mean BMIs (kg/m2) were 22.1 ± 1.6 and 35.9 ± 5.1 in the nonobese and obese groups, respectively. No differences were observed in either the duration of OXT infusion, total dose of OXT, or plasma OXT (pg/mL) either at T0 or T1. However, plasma oxytocinase (ng/mL) was significantly lower at T0 (1.41 [0.67, 3.51] vs. 0.40 [0.29, 1.12]; p = 0.03) in the obese group.

Conclusion We provide preliminary evidence that the disposition of OXT may not be different between obese and nonobese women during labor.

Authors' Contribution

A.D.T.: This author helped design the study, conducted the study, reviewed analysis, wrote, and approved the final article.


J.J.: This author helped conduct the study, reviewed analysis, wrote, and approved the final article.


T.F.M.: This author helped design the study, reviewed analysis, and approved the final article.


J.D.B.: This author performed statistical analysis and approved the final article.


A.P.: This author conceived the study, designed the study, conducted the study, reviewed analysis, wrote, and approved the final article.


Competing Interest

The authors declare no competing interest.