Postural equilibrium during pregnancy: decreased stability with an increased reliance on visual cues

The purpose of this study was to determine whether there are changes in postural equilibrium during pregnancy and to examine whether the incidence of falls increases during pregnancy.

Static postural balance measures were collected from 12 pregnant women at 11 to 14, 19 to 22, and 36 to 39 weeks gestation and at 6 to 8 weeks after delivery and from 12 nulligravid control subjects who were matched for age, height, weight, and body mass index. Subjects were asked to stand quietly on a stable force platform for 30 seconds with eyes open and closed. Path length and average radial displacement were computed on the basis of the average of 3 trials for each condition. The women were asked at each session if they had sustained a fall in the previous 3 months.

Postural stability remained relatively stable during the first trimester; however, second and third trimester and postpartum values for path length and average radial displacement with eyes open and closed were increased significantly compared with the control subjects, which indicates diminished postural balance. The difference between the eyes open and closed values of path length increased as pregnancy progressed. Although 25% of pregnant women sustained falls, none of the control subjects had fallen in the past year.

These data suggest that postural stability declines during pregnancy and remains diminished at 6 to 8 weeks after delivery. The study also indicates that there is an increased reliance on visual cues to maintain balance during pregnancy.