Muscle Tone and motor development in extremely preterm, very preterm, moderate preterm Infant at 8 months of corrected age

The babies born before the completion of 37 weeks of gestation is termed as preterm infants by WHO. They are further classified into extremely preterm infants (<28 weeks), very preterm (28- <32 weeks) and moderate to late preterm (32- <37 weeks) based on their gestational age (1). In every 1000 babies 2-5 babies are born prematurely (2) . Intrauterine and extrauterine growth varies in preterm infants compared to full term infants as they are born prematurely. Muscle tone of preterm infants is reduced due to the maturity related hypotonia. Reduced muscle tone can have an impact in the later development (3). Preterm infants are at greater risk for mortality and variety of developmental and health problems. Complications include acute respiratory, gastrointestinal, immunologic, central nervous system, hearing, and vision problems, as well as longer-term motor, cognitive, visual, hearing, behavioural, social-emotional, health, and growth problems(4).

Motor development varies in preterm infants compared to full term infants (5). Changes in motor development in preterm babies compared to full-term babies can include delays and differences in the achievement of motor milestones, variations in muscle tone, and potential difficulties with coordination and fine motor skill (6).

The preterm infants demonstrate different motor behaviours from their term peers, with an uneven progression of motor skills in different positions from 4 to 8 months of corrected age. At 8 months 90% of the term infants are able to sit without arm support, but only 56% of the preterm infants could maintain sitting very briefly without arm support (5).

It is important to recognise the changes taking place in the different type of preterm infants regarding muscle tone and their interactions with that of the motor development is important for evaluation and treatment planning(7). More precise and periodic assessments should be addressed at an early age to prevent problems in motor development.

At 40 weeks the infants have maturation related hypotonia and the status of maturation related hypotonia is not well known as the child keeps on developing in various preterm infants. The development of muscle tone in the first year of life in various preterm infants is not well established. This study aims to identify the developmental status, muscle tone and its impact on the motor development in various preterm infants at 8th month of corrected age.