Motor asymmetries in preterm infants at 18 weeks corrected age and outcomes at 1 year

Persisting asyymmetries in the motility and posture of preterm infants after term age is a common finding, but their diagnostic and prognostic significance has proved to be difficult to interpret. It has been claimed that if an asymmetry is of central origin, then it should be most prominently detectable in infantile reactions that persist beyond the age when they should have disappeared. We hypothesise that motor asymmetries in preterm infants without a major risk for neurological problems may stem from a high degree of active muscle power in the trunk that continues to be present after 12 weeks corrected age. In order to test this hypothesis, 34 preterm infants with a low risk for neurological complications were compared to a group of 17 fullterm infants at 18 weeks of (corrected) age for the presence or absence of motor asymmetries. None of the full-term infants showed asymmetrical motor behaviour, while within the preterm group a significant number did, in particular those who were small for gestational age. A significant relationship between motor asymmetries and a high degree of muscle power in the trunk at this age was found in the preterm group. Asymmetrical active muscle power at 18 weeks had a good predictive value for asymmetrical locomotor, hand and eye functions at 52 weeks.