Dynamic postural stability during advancing pregnancy.
Pregnant women are at an increased risk of experiencing a fall. Numerous anatomical, physiological, and hormonal alterations occur during pregnancy, but the influence of these factors on dynamic postural stability has not been explored. The purpose of this study was to examine dynamic postural stability in pregnant women during their second and third trimesters as well as in a group of non-pregnant control women.


METHODS
Eighty-one women (41 pregnant, 40 controls) participated stood on a force plate that translated anteroposteriorly at small, medium, and large magnitudes. Reaction time and center of pressure (COP) movement during the translations were analyzed. Trimester, perturbation direction, and perturbation magnitude were the independent variables in a mixed-model analysis of variance on each of the following dependent variables: reaction time, initial sway, total sway, and sway velocity.


RESULTS
Reaction time to the perturbation was not significantly different between the groups. Initial sway, total sway, and sway velocity were significantly less during the third trimester than during the second trimester and when compared to the non-pregnant controls (P<0.05). No differences were found in any of the measures between the pregnant women in their second trimesters and the control group.


CONCLUSIONS
Alterations in sway responses to perturbations are seen in the third trimester in healthy women with uncomplicated pregnancies. Further study is needed to examine the biomechanical and physiological reasons behind this altered dynamic postural stability.
Division of Exercise Physiology, Department of Human Performance and Applied Exercise Science, West Virginia University, 8315 Health Sciences Center South, PO Box 9227, Morgantown, WV 26506-9227, USA. jmccrory@hsc.wvu.edu
J L
JL
McCrory
A J
AJ
Chambers
A
A
Daftary
M S
MS
Redfern
D000058:Accidental Falls; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011247:Pregnancy / Q000502:physiology*; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011930:Reaction Time / Q000502:physiology; D055815:Young Adult