Positioning and baby devices impact infant spinal muscle activity

Emergence of locomotor behaviors: Associations with infant characteristics, developmental status, parental beliefs, and practices in typically developing Brazilian infants aged 5 to 15 months

Independent locomotion provides autonomy for infants, drastically changing their relationship with their surroundings. From a dynamic systems perspective, the interaction between environment, tasks, and organismic constraints leads to the emergence of new behaviors over time. This 6-month longitudinal study aimed to verify associations between the emergence of locomotor behaviors and infants' characteristics, developmental status, parental beliefs, and practices. This observational study remotely assessed 37 full-term Brazilian infants aged 5 to 15 months, divided into two groups (G1: 5 to 11 months, n = 19; and G2: 9 to 15 months, n = 18). The motor developmental status of infants was closely associated with the emergence of behaviors (p < 0.05). Infants in G2 whose parents agreed with the statement "In typically developing infants, motor development occurs naturally and there is no need to actively stimulate it" started to walk later than those whose parents disagreed. Infants whose parents expected them to walk around 10-11 months walked earlier compared to those expected to walk after 11 months (G2, p = 0.011). Infants in G2 with a high frequency of staying in the supine position started to walk, both with and without support, later than those with a low frequency (p < 0.05). For infants in G1 with a high frequency of playing on the floor, locomotion (p = 0.041) and crawling on hands-and-knees (p = 0.007) started sooner compared to those with a low frequency. Staying in the cradle more frequently was related to a later emergence of supported walk (p = 0.046) among infants in G2. The emergence of locomotor behaviors is associated with motor developmental status, the surfaces where the infant plays, and body position. Parental beliefs and expectations influence how infants are stimulated and, consequently, the emergence of independent walking.

Mechanical environment influences muscle activity during infant rolling

An infant's musculoskeletal and motor development is largely affected by their environment. Understanding how different mechanical environments affect an infant's movements and muscle use is necessary to inform the juvenile products industry and reduce incidents involving inclined nursery products each year. The purpose of this study was to determine how the coordinated movements and corresponding muscle activation patterns are affected by different mechanical environments, specifically the back incline angle. Thirty-eight healthy infants (age: 6.5 ± 0.7 months; 23 M/15 F) were enrolled in this IRB-approved in-vivo biomechanics study. Surface electromyography sensors recorded muscle activity of the erector spinae, abdominal muscles, quadriceps, and hamstrings while infants rolled in five different mechanical environments: a flat surface and four device configurations representing a range of inclines infants are commonly exposed to. Coordinated movements were determined using video. In all configurations featuring an inclined seatback angle, infants experienced significantly higher erector spinae muscle activation and significantly lower abdominal muscle activation compared to the flat surface. Infants also exhibited a different coordinated movement featuring spinal extension and a pelvic thrust in the inclined device configurations that was not previously observed on the flat surface alone. Understanding how infants coordinate their movements and use their muscles during rolling in different inclined environments provides more insight into motor development and may inform the juvenile products industry. Many factors impact an infant's movements, therefore future work should explore how other environmental interactions influence an infant's movements and muscle activation, particularly for rolling.

Muscle activation and coordinated movements of infant rolling

Rolling is a critical step of infant development, encouraging muscle coordination and enabling independent exploration. Understanding muscle activity during infant rolling movements on a flat surface is necessary to more fully characterize how the rolling milestone is achieved. The purpose of this study was to determine infants' muscle activation throughout roll initiation for six previously established coordinated movements. Thirty-eight healthy infants (age: 6.5 ± 0.7 months; 23M/15F) were enrolled in this IRB-approved in-vivo biomechanics study. Surface electromyography sensors recorded muscle utilization from the erector spinae, abdominal muscles, quadriceps, and hamstrings while infants rolled. Each rolling movement was categorized as one of six roll types, and the mean muscle activity was analyzed. All roll types required initial activation of all measured muscle groups. Movements featuring axial rotation of the torso relative to the pelvis required highly active erector spinae muscles. Movements featuring trunk and hip flexion required highly active abdominal muscles. Infants used distinct coordinated muscle activations to achieve the six different roll types on a flat surface. A foundational understanding of the different muscle activation patterns required during infant rolling will provide crucial insight into motor development. This study quantified muscle coordination required of infants to achieve rolling on a firm flat surface. Previous research indicates that the mechanical environment in which an infant is placed impacts muscle activity and body position during normal lying. Therefore, future work should explore if mechanical environments that differ from a flat and firm surface also influence these coordinated movements and muscle activations.

Randomized controlled trial to prevent postpartum depressive symptomatology: An infant carrier intervention

BACKGROUND

There is a need for effective interventions to reduce symptomatology of postpartum depression. The objective of this study was to test whether providing an ergonomic infant carrier would reduce postpartum depression symptomatology.

METHODS

A randomized two-arm, parallel-group trial with 100 participants was conducted between February 2018 and June 2019 in a low-income community. At 30-weeks' gestation, 50 participants were randomly assigned to receive an ergonomic infant carrier and instructions on proper use (intervention group), and 50 participants were assigned to a waitlist (control group). Participants tracked the extent of their infant carrier use and completed the Edinburgh Postpartum Depression Scale (EPDS) to assess postpartum depression symptomatology at 6-weeks postpartum.

RESULTS

Participants in the intervention group reported using an infant carrier significantly more often than the control group (β = 2.69, SE = 0.347, p < .001, 95 % CI = 2.08-3.41). The intervention group reported fewer depressive symptoms at 6-weeks postpartum than the control group (β = -0.541, p = .042).

LIMITATIONS

The sample size was relatively small and thus our results may not be generalizable to the general population.

CONCLUSION

Infant carrying may be a cost-effective intervention to reduce postpartum depression symptomatology. Large-scale studies are warranted to further examine the efficacy and cost-effectiveness of providing carriers as an intervention to reduce postpartum depression symptomatology.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov id: NCT04376021. Data Sharing Statement: Deidentified individual participant data will not be made available because we did not obtain permission to share individual data.

CLINICAL TRIAL REGISTRATION NUMBER

NCT0437602; https://beta.

CLINICALTRIALS

gov/study/NCT04376021.

Ultrasonographic evaluation of infant hips in the Pavlik harness compared to body-worn commercial baby carriers

While many factors contribute to development and subsequent correction of developmental hip dysplasia (DDH) in infants, hip positioning and muscle activity play a significant role. Lower-limb restrictive extension positions, such as with swaddling, are detrimental for hip development, and some baby gear leads to reduced lower limb muscle activity. Yet how baby gear impacts hip position during wear remains unclear. The purpose of this study was to compare the Graf's alpha angle and femoral head coverage of healthy infants and infants with mild DDH (instability) in the Pavlik harness and baby carriers. We obtained coronal hip ultrasound images of 10 healthy full-term infants (13.5 ± 3.4 weeks, 5F/5M) and three full-term mild DDH infants (8.9 ± 4.0 weeks, 2F/1M) in three conditions: Pavlik harness, wide-base baby carrier, and narrow-base baby carrier. Repeated measures analysis of variance was used to compare Graf's alpha angles and femoral head coverages across the conditions (p < 0.05), with post hoc pairwise tests (p < 0.0167). The Graf's alpha angle in the narrow-base carrier was 6.9° lower than the Pavlik harness, while the wide-base carrier was not different. Femoral head coverage was 10%-12% lower for the narrow-base carrier. The three mild DDH infants exhibited lower Graf's alpha angles and femoral head coverage in all measurements, with the Graf's alpha angle in the narrow-base carrier measuring 49.0°. This research demonstrated that wide-base baby carriers held hips in a position that was not significantly different from the Pavlik harness, meaning that babywearing in a wide-base carrier may have benefits for healthy hip development.

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.

Characteristics of tummy time and dose-response relationships with development in infants

This study aimed to examine change in tummy time patterns and preferences in the first 6 months of life, as well as dose-response relationships between tummy time duration and development at 2, 4, and 6 months. Participants were parents of infants from the Early Movers project in Edmonton, Canada (baseline: n = 411). At 2, 4, and 6 months, infant tummy time duration and preference (i.e., 1 = really likes to 5 = really dislikes) and development (i.e., Ages & Stages Questionnaire (ASQ-3) communication, fine motor, gross motor, problem-solving, personal-social) were measured by a parental questionnaire. In a subsample (n = 127), tummy time patterns (i.e., bout frequency, mean and median bout length) were measured using a 3-day time-use diary. Tummy time bout frequency, bout length, and preference significantly increased over time. Linear dose-response relationships between tummy time duration and development outcomes were observed at 4 (gross motor) and 6 months (all development outcomes). Moreover, at 2 months, 30-44 min/day of tummy time was associated with a higher total development score (vs. < 15 min/day; B = 11.14; 95%CI: 1.60, 20.68). At 6 months, 61-120 min/day (vs. < 30 min/day; B = 27.12; 95%CI: 11.93, 42.32) and > 120 min/day (vs. < 30 min/day; B = 33.80; 95%CI: 18.90, 48.70) of tummy time were associated with higher total development scores. Differences in threshold doses between some developmental outcomes were observed. Conclusion: In the first 6 months of life, increases were observed in tummy time preference as well as tummy time bout frequent and length. This finding may explain why the optimal amount of tummy time needed for more advanced development appeared to increase with age. What is Known: • Tummy time is a type of physical activity in infancy. International and national guidelines recommend at least 30 minutes of tummy time per day for infants who are not yet mobile. What is New: • In the first six months of life, preference for tummy time as well as tummy time bout frequency and length increased. • Tummy time duration had dose-response associations with several development outcomes, and the optimal amount of tummy time needed for more advanced development appeared to increase with age.

Brazilian Mother’s Practice on Infant Body Position From Birth to 6 Months Old

There is a gap in the understanding of what has been recommended by health professionals to Brazilian mothers regarding infant body positioning whereas the description of this parenting practice can provide criteria for guidance programs already in the maternity ward. This study aimed to record the time (hours/day) Brazilian mothers reported that their infants spent awake or sleeping in 1 of the four body postures: Prone, supine, lateral positions and sitting. The second aim of this study was to verify whether this reported time was associated with birth weight, gestational age, infant chronological age and maternal age. A cross sectional study assessed 92 mothers divided into six groups according to the age of their full-term infant, in months (Mth): 1 Mth (n= 15), 2 Mth (n= 15), 3 Mth (n= 15), 4 Mth (n= 15), 5 Mth (n= 17), and 6 Mth (n= 15). Mothers registered in a 24-hour schedule the most frequent positioning of each infant in 1 day based on the week prior to the assessment day. Infant chronological age was associated with time spent in positions reported by mothers (p< .05). 47.8% of mothers stated not placing infants in prone position anytime in the awake period. Some mothers reported that the infant slept in the prone position. Brazilian caregivers still need to be alerted that the practice of not placing infants to lay in prone might hinder developmental opportunities for them, as well as, on the risks of SIDS and the importance of supine position for infants to sleep.

Comparison of U.S. and Tajik infants' time in containment devices

How infants are held or contained throughout the day shape infants' experiences, particularly around movement and exploration. In Tajikistan, caregivers use "gahvora" cradles, which severely restrict the body and limbs. The present study explored the variability and use of containment devices in U.S. and Tajik infants. Using time diaries, we compared 12-month-olds in the U.S. and Tajikistan on the types of containments used and time spent in them throughout the day. During the day, Tajik infants accumulated more time in gahvoras than infants in the U.S. spent in cribs, primarily used for sleep, suggesting gahvoras served other functions. Given the availability of other devices, U.S. infants' time was distributed in short yet frequent bouts across devices. Accumulated time in these containments matched accumulated time Tajik infants spent in gahvoras. Tajik infants accumulated more unrestricted time on the ground, which was distributed in prolonged bouts, than U.S. infants. Findings highlight differences in infants' everyday experiences during the developmental period when motor skills emerge. By embracing commonalities and exploring differences between cultures, this study offers insights into differences in infants' everyday experiences and opportunities for movement.

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.

Challenges in Kinetic-Kinematic Driven Musculoskeletal Subject-Specific Infant Modeling

Musculoskeletal computational models provide a non-invasive approach to investigate human movement biomechanics. These models could be particularly useful for pediatric applications where in vivo and in vitro biomechanical parameters are difficult or impossible to examine using physical experiments alone. The objective was to develop a novel musculoskeletal subject-specific infant model to investigate hip joint biomechanics during cyclic leg movements. Experimental motion-capture marker data of a supine-lying 2-month-old infant were placed on a generic GAIT 2392 OpenSim model. After scaling the model using body segment anthropometric measurements and joint center locations, inverse kinematics and dynamics were used to estimate hip ranges of motion and moments. For the left hip, a maximum moment of 0.975 Nm and a minimum joint moment of 0.031 Nm were estimated at 34.6° and 65.5° of flexion, respectively. For the right hip, a maximum moment of 0.906 Nm and a minimum joint moment of 0.265 Nm were estimated at 23.4° and 66.5° of flexion, respectively. Results showed agreement with reported values from the literature. Further model refinements and validations are needed to develop and establish a normative infant dataset, which will be particularly important when investigating the movement of infants with pathologies such as developmental dysplasia of the hip. This research represents the first step in the longitudinal development of a model that will critically contribute to our understanding of infant growth and development during the first year of life.

Infant inclined sleep product safety: A model for using biomechanics to explore safe infant product design

Over 450 adverse incidents have been reported in infant inclined sleep products over the past 17 years, with many infants found dead in both the supine and prone positions. The unique design of inclined sleep products may present unexplored suffocation risks related to how these products impact an infant's ability to move. The purpose of this study was to assess body movement and muscle activity of healthy infants when they lie supine and prone on different inclined sleep products. Fifteen healthy full-term infants (age: 17.7 ± 4.9 weeks) were recruited for this IRB-approved study. Three inclined sleep products with unique features, representative of different sleeper designs, were included. Surface electromyography (EMG) was recorded from infants' cervical paraspinal, abdominal, and lumbar erector spinae muscles for 60 s during supine and prone positioning. Neck and trunk sagittal plane movements were evaluated for each testing condition. Paired t-tests and Wilcoxon signed-rank tests were performed to compare each inclined sleeper to a flat crib mattress (0° baseline condition). During prone positioning, abdominal muscle activity significantly nearly doubled for all inclined sleep products compared to the flat crib mattress, while erector spinae muscle activity decreased by up to 48%. Trunk movement significantly increased compared to the flat crib mattress during prone lying. During prone lying, inclined sleep products resulted in significantly higher muscle activity of the trunk core muscles (abdominals) and trunk movement, which has the potential to exacerbate fatigue and contribute to suffocation if an infant cannot self-correct to the supine position.

Getting Babies Safely Home: A Retrospective Chart Review of Car Safety Seat Tolerance Screening Outcomes

BACKGROUND

The American Academy of Pediatrics recommends pre-discharge Car Seat Tolerance Screening (CSTS) for all neonates born <37 weeks estimated gestational age (EGA), or otherwise at risk for cardiorespiratory compromise. Screening is burdensome and there remains tremendous variation in testing criteria and methodology.

DESIGN/METHODS

We conducted a retrospective chart review of 1,072 infants who underwent CSTS between 11/2013 and 7/2016 at a single academic health center. CSTS outcomes (failure and, separately, significant cardiorespiratory instability (CRI)), including those not meeting failure thresholds) were analyzed for all infants screened, and for preterm infants by screening location (Neonatal Intensive Care Unit (NICU) and Mother/Baby Unit (MBU)). Logistic regression was used to estimate associations between infant characteristics and CSTS outcomes.

RESULTS

Overall incidence of CSTS failure was 9.2%. Among all infants, hemodynamically significant congenital heart disease, apnea, chronic lung disease, and being small for EGA were associated with failure. Additionally, those born ≤28 weeks EGA had 2.4 times greater likelihood of failure than those 34-36 weeks EGA. Among preterm infants in the NICU and MBU, those of earlier EGA were also more likely to fail. Almost half (47.5%) of all preterm infants demonstrated CRI during CSTS.

CONCLUSION

We found high CSTS failure rates, and identified key infant characteristics that were associated with increased likelihood of failure. Significant CRI events were remarkably common. Larger, prospective studies are needed to elucidate risk factors for instability and failure and define practical criteria for CSTS recommendations.

Exploring infant hip position and muscle activity in common baby gear and orthopedic devices

Infant positioning in daily life may affect hip development. While neonatal animal studies indicate detrimental relationships between inactive lower extremities and hip development and dysplasia, no research has explored infant hip biomechanics experimentally. This study evaluated hip joint position and lower extremity muscle activity of healthy infants in common body positions, baby gear, and orthopedic devices used to treat hip dysplasia (the Pavlik harness and the Rhino cruiserabduction brace). Surface electromyography(EMG) and marker-based motion capture recorded lower extremity muscle activity and kinematics of 22 healthy full-term infants (4.2±1.6 months, 13M/9F) during five conditions: Pavlik harness, Rhino brace, inward-facing soft-structured baby carrier, held in arms facing inwards, and a standard car seat. Mean filtered EMG signal, time when muscles were active, and hip position (angles) were calculated. Compared to the Pavlik harness, infants exhibited similar adductor activity (but lower hamstring and gluteus maximus activity) in the Rhino abduction brace, similar adductor and gluteus maximus activity (but lower quadriceps and hamstring activity) in the baby carrier, similar but highly variable muscle activity in-arms, and significantly lower muscle activity in the car seat. Hip position was similar between the baby carrier and the Pavlik harness. This novel infant biomechanics study illustrates the potential benefits of using inward-facing soft-structured baby carriers for healthy hip development and highlights the potential negative impact of using supine-lying container-type devices such as car seats for prolonged periods of time. Further study is needed to understand the full picture of how body position impacts infant musculoskeletal development.

Do inclined sleeping surfaces impact infants' muscle activity and movement? A safe sleep product design perspective

The design of inclined sleep products may be associated with an increased risk of suffocation when an infant finds themselves prone in the product. It is important to understand how different inclined sleep surface angles impact infants' muscle activity when considering a safe sleep environment. The purpose of this study was to assess muscle activity of healthy infants when they lie supine and prone on different inclined crib mattress surfaces (0° vs. 10° vs. 20°). Fifteen healthy infants were recruited for this study. Surface EMG was recorded from cervical paraspinal, abdominal, lumbar erector spinae, and triceps muscles for 60 s during supine and prone positioning. Repeated measures ANOVAs and Bonferroni post-hoc adjustments were performed to test the effect of incline angles. Paired t-tests were performed to test the effect of position (supine vs. prone). During prone lying, abdominal muscle activity increased by 33% and 71% for 10° and 20° compared to 0°, while erector spinae and triceps muscle activity decreased for 20° compared to 0°. Lumbar erector spinae and cervical paraspinal muscle activity increased by 185% and 283% for prone compared to supine lying. During prone positioning, the 20° inclined surface resulted in significantly higher muscle activity of the trunk core muscles (abdominals), which may exacerbate fatigue and contribute to suffocation if an infant cannot self-correct to the supine position. Compared to supine positioning, prone lying requires higher musculoskeletal effort to maintain a safe posture to prevent suffocation, and babies likely fatigue faster when lying prone.