Article

Throughout pregnancy, women experience physical, physiological, and hormonal
alterations that are often accompanied by decreased postural control. According
to one study, nearly 27% of pregnant women fell while pregnant. This study had
two objectives: (1) to characterize the postural responses of pregnant fallers,
nonfallers, and controls to surface perturbations, and (2) to develop a
mathematical model to gain insights into the postural control strategies of each
group. This retrospective analysis used experimental data obtained from 15 women
with a fall history during pregnancy, 14 women without a fall history during
pregnancy, and 40 nonpregnant controls. Small, medium, and large translational
support surface perturbations in the anterior and posterior directions were
performed during the pregnant participants' second and third trimesters. A
two-segmented mathematical model of bipedal stance was developed and
parameterized, and optimization tools were used to identify ankle and hip
stiffness, viscosity, and the feedback time delay by searching for the best fits
to experimental COP data. The peak differences between the center of pressure and
center of gravity (COP-COG) values were significantly smaller for the pregnant
fallers compared with the pregnant nonfallers and controls (p<0.01). Perturbation
magnitude was a significant factor (p<0.01), but perturbation direction was not
(p=0.24). Model fits were obtained with a mean goodness of fit value of
R(2)=0.92. Theoretical results indicated that pregnant nonfallers had higher
ankle stiffness compared with the pregnant fallers and the controls, which
suggests that ankle stiffness itself may be the dominant reason for the different
dynamic response characteristics (e.g., peak COP-COG) observed. We conclude that
increasing ankle stiffness could be an important strategy to prevent falling by
pregnant women.
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Langue : ANGLAIS