A longitudinal study to evaluate pregnancy-induced endogenous analgesia and pain modulation

Brendan Carvalho, Michal Granot, Pervez Sultan, Hilary Wilson, Ruth Landau

Research output: Contribution to journalArticlepeer-review

Abstract

Background and Objectives: The phenomenon of pregnancyinduced analgesia has been demonstrated in animal models but less consistently in human studies. This study aimed to assess endogenous pain modulation, evaluating inhibitory and excitatory pain pathways, over the course of pregnancy and postpartum. Methods: Healthy pregnant women were approached for participation in this prospective multicenter cohort study. Conditioned pain modulation (CPM), mechanical temporal summation (mTS), and temperature that induced pain 6 out of 10 (pain-6) were assessed toward the end of each trimester of pregnancy (8-12, 18-22, and 36 weeks) and at 6 to 12 weeks postpartum. To assess how pregnancy affects CPM, mTS, and pain-6, a mixed-effects analysis of variance was performed. Results: Thirty-three pregnant women were enrolled. Pregnancy did not significantly impact CPM (F3,39 = 0.30, P = 0.83, partial η2 = 0.02), and therewas no significant difference between CPMscores in the third trimester compared with postpartum. The mTS scores and pain-6 ratings were also not significantly changed by pregnancy (F3,42 = 1.20, P = 0.32, partial η2 = 0.08; and F3,42 = 1.90, P = 0.14, partial η2 = 0.12, respectively). Conclusions: This is the first study to assess CPM and mTS changes in pregnancy and postpartum. Endogenous pain modulation evaluating both inhibitory and excitatory pain pathways did not significantly change during pregnancy or postpartum. Future studies are required to determine themagnitude and clinical significance of pregnancy-induced analgesia.

Original languageEnglish
Pages (from-to)175-180
Number of pages6
JournalRegional Anesthesia and Pain Medicine
Volume41
Issue number2
DOIs
StatePublished - 2016

Bibliographical note

Funding Information:
The study was supported by the Department of Anesthesia, Perioperative and Pain Medicine, StanfordUniversity, and Department ofAnesthesiology and Pain Medicine, University of Washington. No external funding sources were used. The authors thank Dr Sarah Prager (Department of Obstetrics and Gynecology, University of Washington Medical Center) for her valuable input and help with study design and patient enrollment; Lisa Flint and Jake Kraft, the research coordinators, for performing all of the tests at the University ofWashingtonMedical Center; and Dr Christina Gutierrez and Mihaela Astilean (Lucile Packard Children''s Hospital, Stanford University) for their valuable input and help in patient enrollment and study conduct.

Publisher Copyright:
Copyright © 2016 by American Society of Regional Anesthesia and Pain Medicine.

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

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