Baby carriers: a comparison of traditional sling and front-worn, rear-facing harness carriers

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.

Caregiver-child proximity as a dimension of early experience

Human infancy and early childhood is both a time of heightened brain plasticity and responsivity to the environment as well as a developmental period of dependency on caregivers for survival, nurturance, and stimulation. Across primate species and human evolutionary history, close contact between infants and caregivers is species-expected. As children develop, caregiver-child proximity patterns change as children become more autonomous. In addition to developmental changes, there is variation in caregiver-child proximity across cultures and families, with potential implications for child functioning. We propose that caregiver-child proximity is an important dimension for understanding early environments, given that interactions between children and their caregivers are a primary source of experience-dependent learning. We review approaches for operationalizing this construct (e.g., touch, physical distance) and highlight studies that illustrate how caregiver-child proximity can be measured. Drawing on the concepts proposed in dimensional models of adversity, we consider how caregiver-child proximity may contribute to our understanding of children's early experiences. Finally, we discuss future directions in caregiver-child proximity research with the goal of understanding the link between early experiences and child adaptive and maladaptive functioning.

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.

An analysis of postpartum walking balance and the correlations to anthropometry

BACKGROUND

Falls caused by balance issues during pregnancy are quite common, and these issues can continue postpartum, potentially posing a danger to both the mother and baby. While there has been research on changes to walking gait during pregnancy, walking balance in the postpartum period has yet to be examined. Therefore, the aims of this study were to examine if balance changes persist in postpartum and the contribution of anthropometry changes.

METHODS

This was done through longitudinal observational cohort study at 16 and 40 weeks gestation and at four-week intervals postpartum. Balance was measured as lateral center of mass motion during treadmill walking, and recorded with motion capture cameras following anthropometric measurements. Balance variables were statistically analyzed to observe how they changed over time. Hierarchical regression analyses determined correlations between balance and anthropometry.

RESULTS

Balance was observed to improve significantly just following birth. Additionally, there were changes that continued to indicate improvement throughout the postpartum period. Anthropometry changes were significantly, but minimally, correlated with balance changes.

SIGNIFICANCE

Many women begin to return to normal activities soon after birth. With women participating in various forms of exercise, potentially rigorous work requirements, and tasks around the home, it is important that they, their medical providers, and employers understand and consider the continued risks of imbalance.

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

BACKGROUND

The act of babywearing is recognizably a task of load carriage and has gained popularity among millennial caregivers.

RESEARCH QUESTION

The implications of babywearing on lower extremity joint moments of the caregiver are still unknown during prolonged transport and a direct comparison of babywearing to carrying an infant in-arms has not been previously conducted.

METHODS

Eighteen females participated in this study by performing 3 conditions: a) 3 min walking unloaded (UL), b) 15 min walking while carrying a mannequin infant in-arms (IA), and c) 15 min walking while wearing a mannequin infant in an anteriorly positioned baby carrier (BC). Two separate data analyses were conducted using a repeated measures ANOVA. First, UL compared to the initial minute of walking for IA and BC. Second, UL compared to the final minute of walking for IA and BC.

RESULTS

During initial minute comparisons, both IA and BC conditions increased joint moments in the frontal and sagittal plane at the knee with no change at the ankle and hip. During final minute comparisons, IA maintained the increases in the knee frontal plane joint moments observed during initial minute comparisons but also increased at the hip; however, BC generally showed no statistical difference from UL. Carrying an infant in a baby carrier more closely resembles unloaded walking, while carrying an infant in-arms appears to increase the mechanical load placed on the knee and hip joints in the frontal plane through an increase in joint moments.

SIGNIFICANCE

During prolonged transportation, caregivers might choose to employ a baby carrier as opposed to carrying an infant in-arms, as in-arm carriage increases the loading knee abduction moment by 8.7% and the loading knee extension moment by 16.7%.

Assessing Infant Carriage Systems: Ground Reaction Force Implications for Gait of the Caregiver

Objective To assess the acute alterations of anterior infant carriage systems on the ground reaction force experienced during over-ground walking. Background Previous research has identified the alterations in posture and gait associated with an increased anterior load (external or internal); however, the forces applied to the system due to the altered posture during over-ground walking have not been established. Method Thirteen mixed gender participants completed 45 over-ground walking trials at a self-selected pace under three loaded conditions (unloaded, semi-structured carrier 9.9 kg, and structured carrier 9.9 kg). Each trial consisted of a 15-m walkway, centered around a piezoelectric force platform sampling at 1,200 Hz. Differences were assessed between loaded and unloaded conditions and across carriers using paired samples t tests and repeated measures ANOVA. Results Additional load increased all ground reaction force parameters; however, the magnitude of force changes was influenced by carrier structure. The structured carrier displayed increased force magnitudes, a reduction in the time to vertical maximum heel contact, and an increased duration of the flat foot phase in walking gait. Conclusion Evidence suggests that the acute application of anterior infant carriers alters both kinetic and temporal measures of walking gait. Importantly, these changes appear to be governed not solely by the additional mass but also by the structure of the carrier. Application These findings indicate carrier structure should be considered by the wearer and may be used to inform policy in the recommendation of anterior infant carriage systems use by caregivers.