Effects of infant transportation on lower extremity joint moments: Baby carrier versus carrying in-arms

Infant-carrying methods and their biomechanical influence on maternal gait patterns and joint mechanics

BackgroundInfant carrying is a common practice among caregivers. Carrying loads such as infant mannequins or bags may alter lower extremity joint angles and induce muscle fatigue in the upper extremities of carriers, including men, women, postpartum women, and women who have not given birth. However, the biomechanical effects of various carrying methods on mothers remain poorly understood.ObjectiveThis cross-sectional descriptive study compared the effects of unloaded walking with three infant-carrying conditions on gait mechanics.MethodsThirty healthy mothers' gait parameters were recorded using a motion capture system under four conditions: unloaded walking (UW), front-facing carrying (FC), back-facing carrying (BC), and in arms carrying (IA).ResultsAcross all infant-carrying conditions, notable changes were observed in gait parameters. The front-facing carrying condition elicited the greatest changes in gait mechanics, particularly in pelvis. The in arms carrying condition exhibited minimal changes in gait compared to the back and front-facing carrying conditions. Significant alterations in gait were observed in all infant-carrying conditions compared to unloaded walking (p < 0.05). The results indicated that ankle (M = 41.15 ± 0.25; M = 24.18 ± 0.29; p = 0.0024), and pelvis (M = 6.15 ± 0.35; M = 9.25 ± 0.45; p = 0.0036) movement patterns led to the greatest deviation in gait among four conditions.ConclusionFront-facing carrying imposes the greatest biomechanical and physiological strain while back carrier offers more ergonomically efficient alternative. The in arms carrying method introduces dynamic movement that may affect stability. These findings highlight important considerations for ergonomically optimized infant carriers to support maternal musculoskeletal health and minimize strain.

Design and validation of a questionnaire on habits, health and exercise in the use of baby carriers

INTRODUCTION

Understanding the characteristics and implications of the use of baby carriers can help health care providers understand the habits of their patients and provide guidance to improve quality of life in both children and caregivers. The aim of our study was to design and validate the first self-administered questionnaire to assess babywearing habits and their impact on health and physical activity as a means to monitor musculoskeletal complaints in caregivers.

MATERIAL AND METHODS

350 individuals who currently used or had used baby carrying systems in the last 10 years completed the questionnaire, which was previously subject to a pilot study in a panel of experts. We used exploratory factor analysis to assess the validity of the internal structure of the questionnaire. The Cronbach α coefficient was used to assess reliability. We used varimax rotation to improve the interpretation of the extracted factors.

RESULTS

The factor analysis showed that the questionnaire is appropriate for measuring the dimensions or carriage factors established a priori. It extracted 3 factors each for the constructs of duration and weight of carriage, motivation, exercise habits and effects on infant health and 2 factors for caregiver pain that explained between 55% and 72% of the variance in each construct. The Cronbach α values were greater than 0.5.

CONCLUSIONS

The results support the validity of the questionnaire and demonstrate that it is useful for its intended purpose.

The Combined Influence of Infant Carrying Method and Motherhood on Gait Mechanics

Postpartum mothers are susceptible to lumbopelvic pain which may be exacerbated by loading, like carrying their infant in arms and with baby carriers. Nulliparous women carrying infant mannequins may biomechanically mimic mother-infant dyad, but this has not been studied. The purpose of our study was to investigate biomechanical differences of 10 mothers carrying their infants and 10 nulliparous women carrying infant mannequins under 3 gait conditions: carrying nothing, carrying in arms, and carrying in a baby carrier (babywearing). Spatiotemporal gait parameters, peak ground reaction forces and impulses, and lower extremity and trunk kinematics were collected using motion capture and force plates and compared using a mixed 2 × 3 (parity × condition) analysis of variance (α ≤ .05). The largest differences occurred between carrying conditions: carrying in arms or babywearing increased vertical and anteroposterior ground reaction forces, trunk extension, ankle dorsiflexion, and hip and knee flexion. Kinematic differences were identified between arms and babywearing conditions. Together this suggests alterations in joint loading for both groups. Our study also contributes a novel understanding of postpartum health by demonstrating alterations in step time, anterior forces, and ankle and knee mechanics, suggesting that during gait, mothers carrying their own infants choose different propulsive strategies than nulliparous women carrying mannequins.

Effects of infant care posture and weight on static postural balance

BACKGROUND

Studies investigating postural balance during various infant care postures have not been reported yet.

OBJECTIVE

The aim of this study was to measure static postural balance when holding an infant dummy in-arms and carrying an infant dummy on back according to different infant dummy weights.

METHODS

Sixteen healthy young subjects participated in a balance test. Infant dummies with weights of 4.6 kg (1-month) and 9.8 kg (12-month) were used in this study. All subjects were asked to naturally stand on a force platform in two infant care postures (holding an infant in-arms and carrying an infant on one's back). Center of pressure (COP) was measured from the force platform. Quantitative variables were derived from the COP. Two-way repeated measure analysis of variance (ANOVA) was performed to determine main effects of infant care postures, infant weight, and their interactions on COP variables.

RESULTS

Back carrying a 12-month infant dummy had the greatest amplitude in all COP variables. Back carrying posture showed significantly greater mean distance and peak power, faster mean velocity, and wider COP area compared to holding posture (P< 0.05). There were significant weight effects of most COP variables mainly in AP direction (P< 0.01).

CONCLUSIONS

Our results could contribute to the prevention of musculoskeletal diseases or prevention of fall due to various infant care activities by developing an assisting device to improve postural balance.

Scoping Review of Biological and Behavioral Effects of Babywearing on Mothers and Infants

OBJECTIVE

To synthesize the evidence on the biological and behavioral effects of babywearing on mothers and infants.

DATA SOURCES

We searched PubMed, CINAHL, Embase, PsycINFO, Sociological Abstracts, SCOPUS, and Google Scholar for peer-reviewed, full-text research articles published in English in which researchers reported on the biological or behavioral effects of babywearing on mothers or infants.

STUDY SELECTION

We reviewed the titles and abstracts of 200 records and abstracted 80 for full-text review. Of these, 29 studies met the eligibility criteria and were included in the review.

DATA EXTRACTION

We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) and extracted the following data from the included articles: author(s), year of publication, setting, aim/purpose, design, description, sample, results/outcomes, and implications to practice.

DATA SYNTHESIS

We synthesized data from the included studies into the following eight themes: Increased Contact, Responsiveness, and Secure Attachment; Physiologic Effects; Biomechanics and Positioning; Facilitating and Empowering; Comfort; Maternal Benefits; Speech, Vocalizations, and Tempo; and Beliefs and Perceptions About Babywearing.

CONCLUSION

Babywearing may have a range of beneficial biological and behavioral effects on mothers and infants. The evidence, however, is insufficient to inform practice recommendations, and additional research is warranted.

Analysis of maximum joint moment during infant lifting-up motion

BACKGROUND: Infant care activities can induce musculoskeletal disease. However, little is known about the biomechanical joint load during lifting-up of an infant. OBJECTIVE: The aim of this study was to investigate normalized maximum moment during lifting-up of infant dummies weighing 4.6 kg, 7.6 kg, and 9.8 kg. METHODS: Six healthy young subjects participated in our study. All subjects performed lifting-up activities of dummies to shoulder height with their feet apart and natural postures in their comfortable speed. Three-dimensional reflective marker trajectories and ground reaction forces were used as input to calculate joint moments using a full body musculoskeletal model. Joint moments were normalized by each subject’s body mass. Friedman’s test was performed to compare mean differences of normalized joint moments for lifting up three dummy weights. RESULTS: Lumbar joint had the greatest normalized joint moment. Lumbar and hip extension moments were significantly increased with dummy weight (P< 0.05). In contrast, knee extension and ankle plantarflexion moment were not significantly affected by dummy weight (P> 0.05). CONCLUSIONS: These results indicate that the lumbar joint plays the most important role in infant lifting-up motion and that the load of lumbar and hip joint should be reduced when lifting a heavier infant. These results could contribute to the development of an effective lifting strategy and an assisting device for lifting an infant.

Developmental Dysplasia of Hip and Post-natal Positioning: Role of Swaddling and Baby-Wearing

INTRODUCTION

Traditional swaddling, which implies restrictive immobilisation of the infant's lower limbs with the hips in forced extension and adduction, has been shown to be a risk factor for Developmental Dysplasia of Hip (DDH).

METHODS

We reviewed the literature regarding the correlation between DDH and post-natal positioning by swaddling and baby-wearing, to draw awareness of healthcare professionals towards an important risk factor for DDH that has often been overlooked.

RESULTS

There is overwhelming evidence in the literature, by both experimental and clinical studies, that proves the close association between improper post-natal positioning of the baby's hips in extension-adduction and an increased incidence of DDH. On the other hand, "hip safe" swaddling which allows unrestricted flexion-abduction movements of the infants' hips, and the use of baby-wearing devices which keep the lower limbs in an attitude of hip flexion-abduction and knee flexion, is optimal for hip development. Populations which practice these "hip-safe" techniques of infant immobilisation have a lower incidence of DDH as compared to those which practice restrictive immobilisation. Furthermore, populations which have adopted "hip-safe" positioning have demonstrated a significant decrease in the incidence of DDH. Understanding this association is vital, since this is a modifiable risk factor, rectification of which can decrease the incidence of DDH.

CONCLUSION

Policy makers and governments must design educational campaigns tailored to their respective populations to increase awareness regarding the benefits of "hip-safe" techniques of infant positioning, since this simple intervention has the potential of decreasing the incidence of DDH.

Infant carrying method impacts caregiver posture and loading during gait and item retrieval

BACKGROUND

Human babies are carried by their caregivers during infancy, and the use of ergonomic aids to wear the baby on the body has recently grown in popularity. However, the effects of wearing or holding a baby in-arms on an individual's mechanics during gait and a common object retrieval task are not fully understood.

RESEARCH QUESTION

What are the differences in: 1) spatiotemporal, lower extremity kinematics, and ground reaction force variables during gait, and 2) technique, center of mass motion, and kinematics during an object retrieval task between holding and wearing an infant mannequin?

METHODS

In this prospective biomechanics study, 10 healthy females performed over-ground walking and an object retrieval task in three conditions, holding: (1) nothing (unloaded), (2) an infant mannequin in-arms, and (3) an infant mannequin in a baby carrier. Mechanics were compared using repeated measures ANOVA.

RESULTS

During gait, greater vertical ground reaction force and impulse and braking force was found during the in-arms and carrier conditions compared to unloaded. Significant but small (<5°) differences were found between conditions in lower extremity kinematics. Increased back extension was found during carrier and in-arms compared to unloaded. Step length was the only spatiotemporal parameter that differed between conditions. During object retrieval, most participants used a squatting technique to retrieve the object from the floor. They maintained a more upright posture, with less trunk flexion and anteroposterior movement of their center of mass, and also did not try to fold forward over their hips during the two loaded conditions. Lower extremity kinematics did not differ between unloaded and carrier, suggesting that babywearing may promote more similar lower extremity mechanics to not carrying anything.

SIGNIFICANCE

Holding or wearing an infant provides a mechanical constraint that impacts the forces and kinematics, which has implications for caregivers' pain and dysfunction.