Age of sitting unsupported and independent walking in very low birth weight preterm infants with normal motor development at 2 years

A model for using developmental science to create effective early intervention programs and technologies to improve children's developmental outcomes

Children born with a variety of environmental or medical risk factors may exhibit delays in global development. Very often, such delays are identified at preschool or school age, when children are severely overdue for effective early interventions that can alleviate the delays. This chapter proposes a conceptual model of child development to inform the creation of interventions and rehabilitative technologies that can be provided very early in development, throughout the first year of life, to optimize children's future developmental outcomes. The model suggests that early sensorimotor skills are antecedent and foundational for future motor, cognitive, language, and social development. As an example, this chapter describes how children's early postural control and exploratory movements facilitate the development of future object exploration behaviors that provide enhanced opportunities for learning and advance children's motor, cognitive, language, and social development. An understanding of the developmental pathways in the model can enable the design of effective intervention programs and rehabilitative technologies that target sensorimotor skills in the first year of life with the goal of minimizing or ameliorating the delays that are typically identified at preschool or school age. Specific examples of early interventions and rehabilitative technologies that have effectively advanced children's motor and cognitive development by targeting early sensorimotor skills and behaviors are provided.

Walking Attainment in Very Low Birth Weight Infants in Japan

OBJECTIVE

To clarify the corrected age of walking attainment in very low birth weight infants by birth weight and gestational age, and determine perinatal factors affecting the delay in walking attainment.

METHOD

This was a longitudinal study. We investigated walking attainment and perinatal factors in 145 very low birth weight infants without neurological abnormalities (mean birth weight 1019.3 ± 299.7 g, gestational age 29.0 ± 2.9 weeks). The study infants were stratified by birth weight (group A: <1,000 g, group B: 1,000 g≤, <1,500 g) and gestational age (group I: <28 weeks, group II: 28 weeks≤, <37 weeks) and were compared using unpaired t-tests. Furthermore, we examined the perinatal factors that affect the delay in walking attainment using multiple regression analysis.

RESULTS

Of the walking attainment, infants in Group A were older than those in Group B (50th percentile, 15.8 vs. 14.7 months). Infants in Group I were older than those in Group II (50th percentile, 16.0 vs. 14.8 months). Using multiple regression analysis with walking attainment age as the dependent variable, the duration of mechanical ventilation was found to be significantly related.

CONCLUSION

Very low birth weight infants with light weight and short gestational age have delayed walking attainment, and longer duration of mechanical ventilation increases the risk of delay.

Effects of continued positioning pillow use until a corrected age of six months on cranial deformation and neurodevelopment in preterm infants: A prospective case-control study

BACKGROUND

Preterm infants have a high risk of cranial deformity resulting from external pressures. Such deformity is associated with delayed neurodevelopment.

AIMS

We aimed to clarify the effects of continuous use of positioning pillows on cranial deformity and neurodevelopment in preterm infants.

METHODS

This prospective case-control study was conducted between November 2018 and August 2019. The continuous use of a pillow was initiated after discharge from the neonatal intensive care unit, up to a corrected age of six months. Preterm infants weighing less than 1800 g without neurological abnormalities were included in the study. Patients were divided into two groups: non-pillow group (NP-group) and pillow group (P-group). The primary outcome was the Bayley Scales of Infant Development III (BSID-III) score. We compared asymmetrical cranial deformity and the BSID-III scores in the two groups at a corrected age of six months using the Fisher's exact test and unpaired t-test, respectively.

RESULTS

There were 19 preterm infants (mean gestational age 32.5 ± 1.9 weeks, birth weight 1461.3 ± 244.7) eligible during the study period. The P-group (n = 11) showed asymmetrical cranial deformity at six months less frequently than the NP-group (n = 8) (p = 0.001, Fisher's exact test). Infants in the P-group had significantly higher scores on the BSID-III cognitive scales (95.0 ± 8.4 vs. 86.9 ± 2.6; p = 0.02, unpaired t-test) and fine motor scores on the motor scales (8.6 ± 2.2 vs. 6.6 ± 0.7, p = 0.02, unpaired t-test).

CONCLUSIONS

Continuous pillow use in preterm infants is effective in reducing cranial deformity and improved cognitive and fine motor skills.

TRIAL REGISTRATION

UMIN Clinical Trials Registry, trial no. UMIN000034400 (http://www.umin.ac.jp/ctr/index.htm).

Functional outcomes at 2 years of age following treatment for posthemorrhagic hydrocephalus of prematurity: what do we know at the time of consult?

OBJECTIVE

Posthemorrhagic hydrocephalus of prematurity remains a significant problem in preterm infants. In the literature, there is a scarcity of data on the early disease process, when neurosurgeons are typically consulted for recommendations on treatment. Here, the authors sought to evaluate functional outcomes in premature infants at 2 years of age following treatment for posthemorrhagic hydrocephalus. Their goal was to determine the relationship between factors identifiable at the time of the initial neurosurgical consult and outcomes of patients when they are 2 years of age.

METHODS

The authors performed a retrospective chart review of premature infants treated for intraventricular hemorrhage (IVH) of prematurity (grade III and IV) between 2003 and 2014. Information from three time points (birth, first neurosurgical consult, and 2 years of age) was collected on each patient. Logistic regression analysis was performed to determine the association between variables known at the time of the first neurosurgical consult and each of the outcome variables.

RESULTS

One hundred thirty patients were selected for analysis. At 2 years of age, 16% of the patients had died, 88% had cerebral palsy/developmental delay (CP), 48% were nonverbal, 55% were nonambulatory, 33% had epilepsy, and 41% had visual impairment. In the logistic regression analysis, IVH grade was an independent predictor of CP (p = 0.004), which had an estimated probability of occurrence of 74% in grade III and 96% in grade IV. Sepsis at or before the time of consult was an independent predictor of visual impairment (p = 0.024), which had an estimated probability of 58%. IVH grade was an independent predictor of epilepsy (p = 0.026), which had an estimated probability of 18% in grade III and 43% in grade IV. The IVH grade was also an independent predictor of verbal function (p = 0.007), which had an estimated probability of 68% in grade III versus 41% in grade IV. A higher weeks gestational age (WGA) at birth was an independent predictor of the ability to ambulate (p = 0.0014), which had an estimated probability of 15% at 22 WGA and up to 98% at 36 WGA. The need for oscillating ventilation at consult was an independent predictor of death before 2 years of age (p = 0.001), which had an estimated probability of 42% in patients needing oscillating ventilation versus 13% in those who did not.

CONCLUSIONS

IVH grade was consistently an independent predictor of functional outcomes at 2 years. Gestational age at birth, sepsis, and the need for oscillating ventilation may also predict worse functional outcomes.

Gait Characteristics of Children Born Preterm

Walking is a central skill of daily living. A delay in the onset of walking can be a sign of abnormal motor development. Further, abnormalities in gait can also affect physical functioning. Children born preterm are at significant risk for neurodevelopmental impairments; however, little is known about how preterm birth affects walking. This review describes current evidence of walking in children born preterm with a focus on the age at onset of walking and comparisons of gait characteristics of children born preterm with those born full-term.

Joint Laxity in Preschool Children Born Preterm

OBJECTIVE

To evaluate the prevalence of joint laxity in children born preterm assessed in the first 2 years, the relationship between joint laxity and motor performance at preschool age, and possible changes over time in a subgroup of children followed longitudinally.

STUDY DESIGN

The revised scale of Beighton Score was used to evaluate joint laxity in a population of 132 preschool children born preterm between 24 and 32 weeks of gestational age. All were assessed for joint laxity between 12 and 24 months of age. Children also performed the Movement Assessment Battery for Children-Second Edition between the age of 3 years and 6 months and 4 years; the age at onset of independent walking also was recorded.

RESULTS

The total Beighton Score ranged between 0 and 8. Twenty percent of the cohort showed joint laxity. No differences related to sex or gestational age were observed. Children born preterm with joint laxity achieved later independent walking and achieved lower scores on Movement Assessment Battery for Children-Second Edition than those without joint laxity. In 76 children born preterm, an assessment for joint laxity was repeated once between 25 and 36 months and again after >36 months. No statistically significant difference was observed between the 3 assessments.

CONCLUSIONS

The Beighton Score can be used to assess generalized joint laxity in children born preterm. As the presence of joint laxity influenced motor competences, the possibility to early identify these infants in the first 2 years is of interest to benefit from early intervention and potentially improve gross motor skills and coordination.

Predictors of motor developmental milestones during the first year of life

Studies suggest that both pre- and postnatal factors are predictors of age of attaining milestones in infancy. However, no studies evaluate the comparative strength of these predictors and the amount of the variance in development they explain. This study aimed to conduct a systematic evaluation of a broad selection of possible predictors of age at milestone attainment and to identify factors that explain significant inter-individual variance. Mothers of 5765 children of the Copenhagen Perinatal Cohort (1959-61) recorded 12 developmental milestones prospectively during the child's first year of life. Information on possible predictors was collected during pregnancy and at follow-up and was categorized into the domains: Family background, Pregnancy and delivery, Postnatal influences, and Postnatal growth. The domain Pregnancy and delivery contributed most of the explained variance in Overall mean of milestones (14.4%), with especially gestational age (β = -0.15; p ≤ 0.001) and birth weight (β = -0.16; p ≤ 0.001) being important predictors.

CONCLUSION

Several individual factors, especially gestational age, birth weight, breastfeeding, having lived in a full-time institution, and weight and head increase in the first year, were significantly associated with milestone attainment in the first year of life. Variables within the domain of Pregnancy and delivery explained the largest proportion of variance in milestone attainment compared to the other domains. What is known: • Younger age at attainment of motor developmental milestones positively predicts cognitive outcomes in adulthood. • Both pre- and postnatal factors have been associated with age of attaining milestones in infancy. What is new: • First study to provide a systematic evaluation of a broad selection of predictors of infant milestone attainment. • Variables within the domain of Pregnancy and delivery, especially gestational age and birth weight, explained the largest proportion of variance in milestone attainment. • The variance explained by the predictors decreased time-dependently with later milestones.

Gait in Very Preterm School-Aged Children in Dual-Task Paradigms

OBJECTIVE

The control of gait requires executive and attentional functions. As preterm children show executive and attentional deficits compared to full-term children, performing concurrent tasks that impose additional cognitive load may lead to poorer walking performance in preterm compared to full-term children. Knowledge regarding gait in preterm children after early childhood is scarce. We examined straight walking and if it is more affected in very preterm than in full-term children in dual-task paradigms.

STUDY DESIGN

Twenty preterm children with very low birth-weight (≤ 1500 g), 24 preterm children with birth-weight > 1500 g, and 44 full-term children, born between 2001 and 2006, were investigated. Gait was assessed using an electronic walkway system (GAITRite) while walking without a concurrent task (single-task) and while performing one concurrent (dual-task) or two concurrent (triple-task) tasks. Spatio-temporal gait parameters (gait velocity, cadence, stride length, single support time, double support time), normalized gait parameters (normalized velocity, normalized cadence, normalized stride length) and gait variability parameters (stride velocity variability, stride length variability) were analyzed.

RESULTS

In dual- and triple-task conditions children showed decreased gait velocity, cadence, stride length, as well as increased single support time, double support time and gait variability compared to single-task walking. Further, results showed systematic decreases in stride velocity variability from preterm children with very low birth weight (≤ 1500 g) to preterm children with birth weight > 1500 g to full-term children. There were no significant interactions between walking conditions and prematurity status.

CONCLUSIONS

Dual and triple tasking affects gait of preterm and full-term children, confirming previous results that walking requires executive and attentional functions. Birth-weight dependent systematic changes in stride velocity variability indicate poorer walking performance in preterm children who were less mature at birth.

Preschool motor skills following physical and occupational therapy services among non-disabled very low birth weight children

Children born very low birth weight (VLBW) are at an increased risk of delayed development of motor skills. Physical and occupational therapy services may reduce this risk. Among VLBW children, we evaluated whether receipt of physical or occupational therapy services between 9 months and 2 years of age is associated with improved preschool age motor ability. Using data from the Early Childhood Longitudinal Study Birth Cohort we estimated the association between receipt of therapy and the following preschool motor milestones: skipping eight consecutive steps, hopping five times, standing on one leg for 10 seconds, walking backwards six steps on a line, and jumping distance. We used propensity score methods to adjust for differences in baseline characteristics between children who did and did not receive physical or occupational therapy, since children receiving therapy may be at higher risk of impairment. We applied propensity score weights and modeled the estimated effect of therapy on the distance that the child jumped using linear regression. We modeled all other end points using logistic regression. Treated VLBW children were 1.70 times as likely to skip eight steps (RR 1.70, 95 % CI 0.84, 3.44) compared to the untreated group and 30 % more likely to walk six steps backwards (RR 1.30, 95 % CI 0.63, 2.71), although these differences were not statistically significant. We found little effect of therapy on other endpoints. Providing therapy to VLBW children during early childhood may improve select preschool motor skills involving complex motor planning.

Imitation of 'bye-bye' in very low-birthweight infants

BACKGROUND

The aim of this study was to clarify the development of imitation skills in very low-birthweight (VLBW) infants compared with full-term infants with regard to the onset of 'bye-bye'.

METHODS

A total of 597 full-term infants (age, 6-21 months) and 95 VLBW infants (corrected age, 6-21 months) participated in this study. The time at which the infants began to imitate bye-bye and how they moved their hands were investigated by direct observations of their behaviors.

RESULT

Some full-term infants began to imitate bye-bye at 9 months, and all full-term infants could imitate bye-bye by 16 months old. The imitation of bye-bye was delayed in VLBW infants, but all of them could imitate it at 17 months old. Bye-bye motions were divided into five types. The 'moving wrist up and down' motion was observed most frequently at the initial bye-bye in both groups, but it was more frequent in VLBW infants at the early stage. The motion types changed with age, with the 'palm facing others' motion observed exclusively at 16 months in full-term infants. All infants of both groups could imitate this type at 17 months old.

CONCLUSION

The development of the ability to imitate bye-bye was delayed in VLBW infants even after correction for gestational age. It was suspected that the fine motor development delay might contribute to the late appearance of bye-bye in VLBW infants. Further follow-up study is required to clarify the clinical significance.

Prediction of gross motor development and independent walking in infants born very preterm using the Test of Infant Motor Performance and the Alberta Infant Motor Scale

BACKGROUND

One objective of a neonatal follow-up program is to examine and predict gross motor outcome of infants born preterm.

AIMS

To assess the concurrent validity of the Test of Infant Motor Performance (TIMP) and the Alberta Infant Motor Scale (AIMS), the ability to predict gross motor outcome around 15 months corrected age (CA), and to explore factors associated with the age of independent walking.

METHODS

95 infants, born at a gestational age <30 weeks, were assessed around 3, 6 and 15 months CA. At 3 months CA, correlations of raw-scores, Z-scores, and diagnostic agreement between TIMP and AIMS were determined. AIMS-score at 15 months CA and parental-reported walking age were outcome measures for regression analyses.

RESULTS

The correlation between TIMP and AIMS raw-scores was 0.82, and between Z-scores 0.71. A cut-off Z-score of -1.0 on the TIMP had 92% diagnostic agreement (κ = 0.67) with an AIMS-score < P10. Neither TIMP- nor AIMS-scores at 3 months CA were associated with the gross motor outcome at 15 months CA. The AIMS-scores at 6 months CA predicted the AIMS-scores at 15 months CA with an explained variance of 19%. Median walking age was 15.7 months CA, with which only the hazard ratio of the AIMS at 6 months CA and ethnicity were significantly associated.

CONCLUSIONS

Prediction of gross motor development at 15 months CA and independent walking was not possible prior to 6 months CA using the AIMS, with restricted predictive value. Cultural and infant factors seem to influence the onset of independent walking.

Grounding early intervention: physical therapy cannot just be about motor skills anymore

This perspective article provides support for 4 interrelated tenets: grounded perceptual-motor experience within cultural and social contexts forms cognition; exploration through early behaviors, such as object interaction, sitting, and locomotion, broadly facilitates development; infants and children with limited exploration are at risk for global developmental impairments; and early interventions targeting exploratory behaviors may be feasible and effective at advancing a range of abilities across developmental domains and time. These tenets emphasize that through the promotion of early perceptual-motor behaviors, broader, more global developmental advancements can be facilitated and future delays can be minimized across domains for infants and children with special needs. Researchers, educators, and clinicians should build on these tenets to further demonstrate the effectiveness of targeted early interventions. The goals of these interventions should be not only to advance targeted perceptual-motor skills in the moment but also to more broadly advance future abilities and meet the early intervention goal of maximizing children's learning potential.

Desenvolvimento motor e funcional em crianças nascidas pré-termo e a termo: influência de fatores de risco biológico e ambiental

OBJETIVO: Comparar o desenvolvimento motor de crianças de 12 a 18 meses nascidas pré-termo e a termo e investigar sua relação com o desempenho funcional e com a quantidade e qualidade de estímulos ambientais. MÉTODOS: Estudo quantitativo e longitudinal com 30 crianças prematuras (idade gestacional de 30,0±2,3 semanas e peso ao nascimento de 1178±193g) e 30 nascidas a termo (idade gestacional de 39,0±1,3 semanas e peso ao nascimento de 3270±400g). O desenvolvimento motor foi avaliado pelos testes Alberta Infant Motor Scale e Peabody Developmental Motor Scales. O ambiente domiciliar foi avaliado com o Home Observation Measurement of the Environment. Com o intuito de examinar as habilidades funcionais, utilizou-se o Pediatric Evaluation of Disability Inventory. RESULTADOS: Houve maior lentidão para aquisição da marcha no grupo pré-termo (p=0,005), embora não tenha sido encontrada diferença significativa entre os grupos no Alberta Infant Motor Scale aos 12 (p=0,19) e aos 15 meses (p=0,80). Aos 18 meses foram encontradas diferenças significativas no desenvolvimento motor grosso (p<0,001) e fino (p=0,001) e nas habilidades funcionais, com vantagem para o grupo a termo. Houve diferença significativa entre os grupos quando avaliados pelo inventário Home Observation Measurement of the Environment (p=0,008). CONCLUSÕES: Houve aumento da diferença entre os grupos no desempenho motor dos 12 aos 18 meses, sendo que fatores ambientais podem ter potencializado os efeitos do risco biológico. Programas de acompanhamento do desenvolvimento devem enfocar aspectos do ambiente onde a criança vive.

Vestibular impairment after bacterial meningitis delays infant posturomotor development

OBJECTIVE

To examine the findings and impact of postmeningitis vestibular dysfunction on early posturomotor development. Meningitis in children is frequently associated with postural instability, which is often attributed to an undefined neurologic disorder but it could actually be due to vestibular impairment.

STUDY DESIGN

In a retrospective cohort study, we compared groups with vestibular loss before versus after independent walking: 37 children (18 girls, 19 boys; median age: 2.3 years) hospitalized for bacterial meningitis and referred for postural instability. A complete vestibular evaluation included 3 tests for function of the 6 semicircular canals (caloric, earth vertical axis rotation, head impulse tests), 2 tests for otolith function assessment (vestibular evoked myogenic potentials, off vertical axis rotation), audiologic evaluation, neurologic examination, and brain and temporal bone imaging.

RESULTS

Twenty-nine children (10.5% of the 276 children hospitalized with bacterial meningitis) had vestibular impairment. Vestibular loss was complete bilaterally in 16 of 37 children and partial in 13 of 37, and 8 cases had normal vestibular responses. Neurologically normal children who had meningitis before they walked independently and had complete bilateral vestibular loss walked significantly later and their postural instability lasted longer than children in the other groups. The degree of vestibular impairment correlated with the postural instability duration and with the degree of hearing loss.

CONCLUSIONS

Bacterial meningitis in young children can impair vestibular function completely, leading to delayed posturomotor development if meningitis occurs before independent walking, even in absence of neurologic impairment. Vestibular evaluations are encouraged for postmeningitis evaluation, particularly in cases with postural instability exceeding 8 days, hearing impairment, and programmed cochlear implant.

Differences in walking attainment ages between low-risk preterm and healthy full-term infants

OBJECTIVE: To compare gross motor development of preterm infants (PT) without cerebral palsy with healthy full-term (FT) infants, according to Alberta Infant Motor Scale (AIMS); to compare the age of walking between PT and FT; and whether the age of walking in PT is affected by neonatal variables. METHODS: Prospective study compared monthly 101 PT and 52 FT, from the first visit, until all AIMS items had been observed. Results: Mean scores were similarity in their progression, except from the eighth to tenth months. FT infants were faster in walking attainment than PT. Birth weight and length and duration of neonatal nursery stay were related to walking delay. CONCLUSION: Gross motor development between PT and FT were similar, except from the eighth to tenth months of age. PT walked later than FT infants and predictive variables were birth weight and length, and duration of neonatal intensive unit stay.

Worldwide implementation of the WHO Child Growth Standards

OBJECTIVE

To describe the worldwide implementation of the WHO Child Growth Standards ('WHO standards').

DESIGN

A questionnaire on the adoption of the WHO standards was sent to health authorities. The questions concerned anthropometric indicators adopted, newly introduced indicators, age range, use of sex-specific charts, previously used references, classification system, activities undertaken to roll out the standards and reasons for non-adoption.

SETTING

Worldwide.

SUBJECTS

Two hundred and nineteen countries and territories.

RESULTS

By April 2011, 125 countries had adopted the WHO standards, another twenty-five were considering their adoption and thirty had not adopted them. Preference for local references was the main reason for non-adoption. Weight-for-age was adopted almost universally, followed by length/height-for-age (104 countries) and weight-for-length/height (eighty-eight countries). Several countries (thirty-six) reported newly introducing BMI-for-age. Most countries opted for sex-specific charts and the Z-score classification. Many redesigned their child health records and updated recommendations on infant feeding, immunization and other health messages. About two-thirds reported incorporating the standards into pre-service training. Other activities ranged from incorporating the standards into computerized information systems, to providing supplies of anthropometric equipment and mobilizing resources for the standards' roll-out.

CONCLUSIONS

Five years after their release, the WHO standards have been widely scrutinized and implemented. Countries have adopted and harmonized best practices in child growth assessment and established the breast-fed infant as the norm against which to assess compliance with children's right to achieve their full genetic growth potential.

The forward parachute reaction and independent walking in infants with brain lesions

AIM

The aim of this study was to assess the onset of forward parachute reaction (FPR) in infants with brain lesions and its correlation with age of walking.

METHOD

FPR was assessed at 6, 9, and 12 months in 140 infants with brain lesions (78 males, 62 females; mean gestational age 31 wks; SD 3.6 wks; mean birthweight 1450 g, SD 252 g). On cranial ultrasound 62 infants had mild and 78 had major abnormalities; 86 developed cerebral palsy. All were followed for 5 years, and the age at which each child achieved independent walking was recorded. Infants who had been born small for gestational age (weight <10th centile) were excluded, as were those who had major congenital malformations, severe postnatal infectious diseases, or metabolic or haematological complications.

RESULTS

A complete FPR was present in eight infants at 6 months, in 42 at 9 months, and in 71 at 12 months. At 12 months, 29 infants presented incomplete FPR and 40 presented absent FPR. Seventy-three infants were able to walk independently between the ages of 11 months and 60 months (67 with complete FPR and six with incomplete FPR at 12 mo). A complete FPR at 12 months was a good predictor of independent walking. The age at onset of complete FPR was also a good predictor of age of walking.

INTERPRETATION

The late acquisition of a complete FPR appears to be an early sign of a more general delayed maturation of functional abilities.

Effects of secondhand smoke exposure on the health and development of african american premature infants

Objective. To explore the effects of secondhand smoke exposure on growth, health-related illness, and child development in rural African American premature infants through 24 months corrected age. Method. 171 premature infants (72 boys, 99 girls) of African American mothers with a mean birthweight of 1114 grams. Mothers reported on household smoking and infant health at 2, 6, 12, 18, and 24 months corrected age. Infant growth was measured at 6, 12, 18, and 24 months, and developmental assessments were conducted at 12 and 24 months. Results. Thirty percent of infants were exposed to secondhand smoke within their first 2 years of life. Secondhand smoke exposure was associated with poorer growth of head circumference and the development of otitis media at 2 months corrected age. Height, weight, wheezing, and child development were not related to secondhand smoke exposure. Conclusion. Exposure to secondhand smoke may negatively impact health of rural African American premature infants. Interventions targeted at reducing exposure could potentially improve infant outcomes.

Reaching strategies of very preterm infants at 8 months corrected age

Reaching strategies and kinematics for a group of very preterm infants were investigated and compared with a group of full-term infants when reaching for a moving object. Eight-month-old (corrected-age) infants were presented with small toys moving on a semicircular path in the vertical plane. The trajectories of the target and the hands of the infants were measured using a 3D motion analysis system. No differences were found in how often the infants encountered the target. The very preterm group, however, used bimanual strategies more often and had more curved reaching paths than the full-term group. These results suggest that very preterm infants are equally successful as healthy full-term infants in catching a moving object but their reaching strategies are less efficient compared with full-term infants at 8 months (corrected age).

Sensing movement: microsensors for body motion measurement

Recognition of body posture and motion is an important physiological function that can keep the body in balance. Man-made motion sensors have also been widely applied for a broad array of biomedical applications including diagnosis of balance disorders and evaluation of energy expenditure. This paper reviews the state-of-the-art sensing components utilized for body motion measurement. The anatomy and working principles of a natural body motion sensor, the human vestibular system, are first described. Various man-made inertial sensors are then elaborated based on their distinctive sensing mechanisms. In particular, both the conventional solid-state motion sensors and the emerging non solid-state motion sensors are depicted. With their lower cost and increased intelligence, man-made motion sensors are expected to play an increasingly important role in biomedical systems for basic research as well as clinical diagnostics.

[Ages of sitting up and walking in preterm newborns less than 1,500 G with bronchopulmonary dysplasia]

INTRODUCTION

Adverse neurological events in very low birth weight (VLBW) children with bronchopulmonary dysplasia (BPD) are more frequent than in children without. An understanding of the ages when preterm infants acquire certain motor skills will give parents more appropriate information on motor development. The objective of the present study is to estimate the influence between BPD and the age of acquisition of sitting unsupported and independent walking in VLBW children with normal neurological examination at 2 years of corrected age.

PATIENTS AND METHODS

A longitudinal study was conducted on a cohort of 885 children with VLBW, admitted to the Hospital "12 de Octubre" between January 1991 and December 2003. Age for both skills was established by interview with parents. Means were compared with t-test and Bonferroni adjustment where appropriate.

RESULTS

Both motor skills were acquired later in the group with BPD (7.8±2m vs. 7.1±1.3m for sitting unsupported and 14.5±3.8m vs. 13.4±2.5m for walking) (P<.001). BPD was associated with delayed acquisition (above p90) of these skills, OR=2.6 (1.6-4.1) for sitting and OR=2.8 (1.6-4.8) for walking. Association was found after adjusting for gestational age (GA) and weight.

CONCLUSION

BPD was associated with delayed acquisition of both skills in VLBW children with normal neurological examination at 2 years.