Related Experiment Video
Updated: Aug 15, 2026
A Preterm Rat Model for Pain Studies
Published on: February 9, 2024
Body movements: an important additional factor in discriminating pain from stress in preterm infants
Liisa Holsti1, Ruth E Grunau, Tim F Oberlander
1Centre for Community Child Health Research, British Columbia Research Institute for Children's and Women's Health, Vancouver, British Columbia, Canada. lholsti@cw.bc.ca
Insights
Routine care like diaper changes causes more stress cues in preterm infants than acute pain, with effects lasting longer. Observing specific body movements alongside facial activity and heart rate offers a more complete pain assessment.
Area of Science:
- Neonatal care
- Developmental pediatrics
- Pain and stress assessment in infants
Background:
- Preterm infants exhibit distinct biobehavioral responses to caregiving and pain.
- Assessing pain and stress in preterm infants requires understanding nuanced responses.
- Routine caregiving tasks can elicit significant physiological and behavioral changes.
Purpose of the Study:
- To characterize specific body movements and biobehavioral responses of preterm infants during routine care (Clustered Care).
- To compare infant responses to Clustered Care with responses to acute pain (Lance/squeeze).
Main Methods:
- A randomized study of 54 preterm infants at 32 weeks gestational age.
- Assessment during blood collection and routine care (diaper change, mouth care).
- Utilized Newborn Individualized Developmental Care and Assessment Program (NIDCAP), Neonatal Facial Coding System (NFCS), heart rate, and oxygen saturation monitoring.
Main Results:
- Acute pain (Lance/squeeze) increased heart rate, Brow Bulge (NFCS), and NIDCAP movements, while decreasing oxygen saturation.
- Clustered Care elicited similar but less intense facial and physiological changes.
- Clustered Care resulted in more frequent and varied NIDCAP stress cues that persisted longer than those from Lance/squeeze.
Conclusions:
- Facial activity and heart rate are sensitive pain markers in preterm infants.
- Tactile procedures cause less intense facial/physiological responses but more prolonged body reactions than painful procedures.
- Integrating NIDCAP body movements enhances pain and stress assessment, especially in infants with dampened facial reactivity.
Objectives:
To describe developmentally appropriate, specific body movements and other biobehavioral responses of preterm infants to a group of routine care giving tasks (Clustered Care), and to compare responses to acute pain with those of Clustered Care.
Methods:
In a randomized design, 54 preterm infants were assessed at 32 weeks gestational age during 3 phases of blood collection (Baseline, Lance/squeeze, Recovery) and of diaper changing, measuring abdominal girth and axillary temperature, and mouth care (Baseline, Clustered Care, Recovery) in a neonatal intensive care unit. The Newborn Individualized Developmental Care and Assessment Program and 1 facial action from the Neonatal Facial Coding System, Brow Bulge, were coded from separate continuous bedside video recordings. Heart rate and oxygen saturation were also acquired continuously.
Results:
Brow Bulge, heart rate, and a subset of 9 Newborn Individualized Developmental Care and Assessment Program movements increased and oxygen saturation decreased significantly to Lance/squeeze compared to Baseline. Similar facial and physiological changes occurred during Clustered Care, but with less intensity. However, infants showed greater frequencies and variety of Newborn Individualized Developmental Care and Assessment Program stress cues during Clustered Care than during Lance/squeeze. Stress cues persisted after Clustered Care, whereas the infants returned to Baseline following Lance/squeeze.
Discussion:
Changes in facial activity and heart rate remain the most sensitive markers of pain in preterm infants. Tactile procedures, such as diaper changing, produce lower intensity facial and physiological responses than pain procedures, but greater body reactions. Also, the effects from tactile procedures appear to last longer. Adding observations of a small number of specific body movements to the assessment of pain and stress provides complementary information particularly for those infants who may show dampened facial reactivity as a result of repeated pain exposure.
