Relationship between the parachute reactions and standing and walking in normal infants.

Assumption of the vertical position and independent walking are potentially hazardous motor milestones in the developing infant. It has been presumed that the parachute reactions evolved to protect infants from injury during this developmental stage. To determine the relationship between the appearance of the upper and lower parachute reactions and the developmental milestones of unsupported standing and independent walking, 190 normal infants were prospectively studied. The upper parachute reaction was found to precede the lower by less than a month (mean age of appearance: 8.9 and 9.2 months, respectively). More than one-half of the cohort achieved standing without either the upper (49%) or lower parachute reaction (57%); however, no independent walking occurred without the upper parachute reaction, and only 2 of 190 infants (1%) walked independently without the lower parachute reaction. Onset of walking occurred about 4 months after the appearance of the upper parachute reaction. The significance of these findings is discussed.