Endogenous Pain Facilitation and Inhibition in Postpartum Women

This study seeks to further understand these three observations - (1) that the time period surrounding childbirth accelerates recovery from pain after injury (2) that this likely reflects dampened facilitating mechanisms and exaggerated inhibitory mechanisms, and (3) that stress may interfere with this protection. In this study the investigators will compare women within 2 weeks of delivery to age matched controls and anticipate that pain inhibition is increased after delivery, pain facilitation is decreased, and that there is a relationship between these pain responses and the degree of pre-existing stress.

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Key information

Conditions

Pain Inhibition and Facilitation in Post Partum Women Behavior Inhibition, Psychological Neurologic Manifestations Pain Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year and older

Sex eligibility

Female

Study type

Observational

Primary location

Wake Forest Baptist Medical Center

Winston-Salem, North Carolina, 27157, United States

About this study

Nearly half of the world's population experiences labor and delivery processes which are associated with microscopic or gross tissue injury to the mother. Since this experience is widespread and occurs relatively early in life, the psychosocial, medical, and financial consequences of chronic pain following childbirth could be enormous. Surprisingly, previous studies with long term follow up of new mothers have included pain as a secondary measure and / or have focused on prevalence of pain without determining whether pain predated delivery or even pregnancy itself. The investigators recently performed a long term follow up study of over 1,200 women, and noted that pain which began during the childbirth itself was surprisingly rare in comparison to other physical injuries. Additionally, two central factors hypothesized to confer risk of chronic pain after other injuries including surgery, pre-dating chronic pain and degree of tissue and nerve injury, contributed minimally to the acute and sub-acute pain after childbirth. These two observations, low incidence of chronic pain and minimal effect of degree of tissue injury and history of chronic pain on sub-acute pain, point towards a potential protective effect of pregnancy or delivery on the response to physical injury.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

female
10-14 days postpartum, term vaginal delivery
breastfeeding (postpartum women)
health non-pregnant female (nulliparous or at least 1 year beyond delivery)

Exclusion criteria

Allergy to chili peppers
pregnant
pain medication (narcotic or non-narcotic) within 4 hours of study visit Average pain in the 24 hours preceding the study visit >3. Postpartum women that score >13 on the Edinburgh Postnatal Depression Scale

Treatment and study plan

Primary outcomes

Area of hyperalgesia will be the primary outcome measure

Time frame: 40 minutes post capsaicin application

Hyperalgesia and allodynia on the skin of the forearm will be established by heating the forearm with a 4 cm2 Peltier controlled thermode (TSA®) to 45 degrees Celsius for 5 minutes. The investigators will then apply topical capsaicin (0.075% cream, Bioglan Pharmaceuticals) under an occlusive dressing at the same site as the thermal probe for 30 minutes. 40 minutes after removal of the capsaicin cream the site will be heated to 40 degrees Celsius for 5 minutes (rekindling) following the end of capsaicin application. The investigators will test skin sensations with the filament and cotton wisp after this heating.
Percent reduction in degree of pain to the 49 degrees Celsius stimulus during the time the foot is immersed in the cold water

Time frame: 15 minutes

Conditioned pain modulation will be induced by placing a foot in a container of circulating water maintained at 10 degrees Celsius for 90 seconds. Thirty seconds after the foot is placed into container of circulating water, the stimulus response to heat on the contralateral forearm will be measured using a 49 degrees Celsius stimulus for 5 seconds. The foot will then be withdrawn and warmed with warm blankets. The stimulus response to heat stimuli on the arm will be measured 5 and 15 min thereafter.

Sponsors and collaborators

Lead sponsor

Wake Forest University

Other

Registry information

Important dates

Study start: 2013
Primary completion: 2017
Study completion: 2017
First posted: Apr 30, 2013
Registry last updated: Dec 19, 2017

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

Completed