Infants born preterm may be less able to perform certain motor and exploratory behaviors, which could lead to future cognitive and developmental delays, suggests a study in the September issue of PTJ. According to the study's authors, physical therapists in early-intervention programs should target behaviors such as head control and ability to make a fist.

Non-object-oriented exploration, wrote the authors, "is not only critical for infants to learn how to engage in social interactions and to learn about objects; it is also key for infants to learn to control their own bodies so they can perform perceptual-motor behaviors like lifting their heads against gravity, reaching, or moving their hands into midline.”

Researchers followed the development of 24 healthy full-term infants (37–42 weeks gestational age), 24 infants born preterm, and 6 preterm infants who were born with brain injury.

Authors recorded the infants in their home environments just after expected date of birth, and at 1.5, 3, 4, 6, 9, 12, 18, and 24 months of age. Through 9 months, they assessed the infants in lying on their backs and on their stomachs. From 3 months through 24 months, they assessed the infants in sitting, supported in an infant seat.

Some of the findings include:

Holding up the head. Through the age of 9 months, all infants improved their ability to hold up their heads while lying on their stomachs, but those born preterm were less able.

Holding the head in midline. In the prone position, all infants improved, but full-term infants showed the greatest ability and preterm infants with brain injury the least. Full-term infants also were best able to hold their heads in midline while lying on their backs, but there was no significant difference between preterm infants with and without brain injury. There was no significant difference among the groups in ability to hold the head in midline while sitting.

Holding 1 hand in midline. While lying on their backs, there was no significant difference among the groups. Full-term infants did so more frequently in prone or sitting position, with no significant differences between preterm infants with and without brain injury.

Holding both hands in midline. In supine position, there was no significant difference among the groups. While prone, preterm infants with brain injury exhibited difficulty. In sitting position, full-term infants showed greater ability than all preterm infants.

Holding hands fisted. The amount of time spent holding 1 or both hands fisted decreased for all infants over time. However, through 9 months, infants with brain injury demonstrated more 1-handed fisting while lying down; all preterm babies showed more 1-handed fisting while sitting than did the full-term infants. Full-term infants in prone position spent more time with both hands fisted over the first 6 months than did the other 2 groups.

Hand mouthing. Preterm infants with brain injury showed more hand mouthing than the other groups while prone but less while supine. There was no difference while sitting.

Touching the body or surfaces. Touching the body decreased for all infants over 9 months, but preterm infants with brain injury did so much less frequently than the other groups. Touching surfaces increased over 9 months for all infants in prone and supine. While there were no differences among the groups for touching surfaces in prone position, full-term infants did so the least frequently, and infants with brain injury the most frequently. While sitting, the trajectory was the same for all groups over 24 months.

Bouts of exploration per minute. At 6 months of age, infants without brain injury performed 7% more bouts of exploration per minute while sitting than did preterm infants with brain injury; this difference increased to 74.6% by 18 months of age.

Variety of separate and combined behaviors. Full-term infants performed a greater variety of both separate and combined behaviors while prone. There were no differences among the groups while supine. In sitting, full-term infants performed a greater variety of combined behaviors, and all infants without brain injury demonstrated a greater variety of separate behaviors.

The authors wrote that these non-object-oriented exploratory behaviors can "provide proprioceptive and haptic feedback, increase their body awareness, and are believed to be the precursors of future reaching and grasping behaviors.” Impairments in this area, they concluded, "are likely to cascade into delays in reaching and object exploration, which in turn will result in future motor and cognitive delays,” which proper early intervention could address.