The Stepping Response in Early Infancy

Postnatally, the stepping response can be elicited right after birth, but soon diminishes and disappears by about 2 - 3 months of age. It is still not clear if the disappearance of the response is caused by gradual maturation of the central nervous system, environmental factors, or biomechanical factors such as added body weight and/or increased muscle mass of the legs. This clinical study assessed the stepping response in a group of healthy infants (n = 58) at the age of 6 weeks: 37 born preterm and corrected for gestational age. Quantitative measures of stepping response were obtained together with the qualitative measures of behavioural state and the distribution of active and passive muscle power of the legs. Mechanical factors were studied by dividing the infants according to their birth weight status, and calculating the ponderal index (PI), leg volume (LV), and weight gain of each group. Preterm infants show more stepping responses, more muscle power discrepancies, and different leg volumes than their full-term counterparts. In addition, our results reported significant relationship between gestational age and relative birth weight on the manifestation of stepping response. Within the preterm group the responses lingered longer in infants with shorter gestational ages and in those with lower birth weight status. Consequently, this study suggests that environmental experience and the time of birth of the infants play a more significant role than maturation and mechanical factors in the manifestation of the infantile stepping response.

Stepping response - Preterm and full-term infants - Maturation - Environmental experience - Muscle mass

References

• 1 Casaer P. Postural behavior in newborn infants. Clinics in Developmental Medicine (No. 72). Spastics International Medical Publications. London; William Heinemann Medical Books 1979
• 2 Dubowitz L M, Goldberg C. Assessment of gestation by ultrasound in various stages of pregnancy in infants of differing size and ethnic origin.  Br J Obstet Gynaecol. 1981;  88 255-259
• 3 Forssberg H. Ontogeny of human locomotor control. I. Infant stepping, supported locomotion and transition to independent locomotion.  Exp Brain Res. 1985;  57 480-493
• 4 Forssberg H. Development and integration of human locomotor unctions. Goldberger ME, Gorio A, Murray M Fidia Research Series: Development and Plasticity of the Mammalian Spinal Cord. 3. Padova; Liviana Press 1986: 53-62
• 5 Gorga D, Stern F M, Ross G, Nagler W. Neuromotor development of preterm and full-term infants.  Early Human Dev. 1988;  18 137-149
• 6 Groot de L, Hoek van der A M, Hopkins B, Touwen B CL. Development of the relationship between the active and passive muscle power in preterms after term age.  Neuropediatrics. 1992;  23 298-305
• 7 Groot de L. Posture and Motility in Preterm Infants. Amsterdam; Free University Press 1993
• 8 Groot de L, Groot de C J, Hopkins B. An instrument to measure independent walking: Are there differences between PT and FT infants?.  J Child Neurology. 1997;  12 37-42
• 9 Illingworth R S. The Development of the Infant and Young Child, Normal and Abnormal. Edinburgh; Livingstone 1973
• 10 Katona F. Fejlõdésneurológia, neurohabilitáció (Developmental neurology, neurohabiliation). Budapest; Medicina Könyvkiadó 1986
• 11 Kloosterman J J. Referentie warden geboortegewicht.  Int J Obstet Gynecol. 1970;  8 885-912
• 12 Oppenheim R W. Ontogenetic Adaptations in Neural and Behavioural Development Toward a More “Ecological” Development Psychobiology.  Continuity of Neural Functions. Spastic Intern. Publications. Oxford; Blackwell 1984: 16-28
• 13 Peiper M C, Darrah J, Byrne P. Impact of gestational age on preterm motor development at 4 months chronological and adjusted age.  Child Care Health Dev. 1989;  15 105-116
• 14 Prechtl H FR. Assessment and significance of behavioral states. Berenberg SR Brain, Fetal and Infant. The Hague; M. Seythoff Med. Pub , 1977: 79-90
• 15 Prechtl H FR. Continuity of Neural Functions from Prenatal to Postnatal Life. Development Medicine. Oxford; Blackwell 1994: 245-247
• 16 Saint Anne Dargassies .Neurological Development in the Full-Term and Premature Neonate. Amsterdam; Experta Medica 1977
• 17 Saint-Anne Dargassies. The Neuro-Motor and Psycho-Affective Development of the Infant. Amsterdam; Elsevier 1986
• 18 Samsom J F, Groot de L. Muscle power and medical history in high risk preterm infants at 3 months of corrected age.  Neuropediatrics. 1998;  29 127-132
• 19 Thelen E, Fisher D M. Newborn stepping: an explanation for a “disappearing” reflex.  Dev Psychol. 1982;  18 760-775
• 20 Thelen E, Fisher D M, Ridley-Johnson R, Griffin N. Effects of body build and arousal on newborn stepping.  Dev Psychobiol. 1982;  15 447-453
• 21 Thelen E. Learning to walk is still an “old” problem: A reply to Zelazo.  J Motor Behaviour. 1983;  15 139-161
• 22 Thelen E, Fisher D M, Ridley-Johnson R. The relationship between physical growth and a newborn reflex.  Infants Behavior Dev. 1984;  7 479-493
• 23 Thelen E. Learning to walk: Ecological demands and phylogenetic constraints.  Adv Infancy Res. 1984;  3 213-250
• 24 Womersley J, Durnin J VGA. A comparison of the skinfold method with extent of overweight and various weight-height relationships in the assessment of obesity.  Br J Nutr. 1977;  38 271-284
• 25 Zelazo P R. The development of walking: New findings and old assumptions.  J Motor Behavior. 1983;  15 99-137
• 26 Zelazo P R. “Learning to walk”. Recognition of higher order influences?.  Adv Infancy Res. 1984;  3 251-256