A longitudinal study of early leg postures of preterm infants.

The prone and supine resting postures of the pelvis and legs of 106 preterm infants (25 to 34 weeks gestation) were studied longitudinally between 30 and 38 weeks post-menstrual age. All the infants subsequently had normal motor development. Posture was graded in relation to three items: the angle of elevation of the pelvis and the weight-bearing surface of the knee in prone, and the angle of rotation of the leg in supine. Although no grade was found to be exclusive to a particular postmenstrual age, all three items showed a statistically significant progressive trend. Only less than 6 per cent of the infants regressed in grade during the study. Infants dependent on oxygen for more than 28 days had significantly lower grades for leg posture in both prone and supine. Posture was not significantly altered by time ex utero or by intra-uterine growth retardation. The results show that these observation items are suitable measures of the progressive development of antigravity postures of preterm infants.