page_title: Maternal physiological changes in pregnancy
section_title: Response to perturbations
hierarchical_section_title: Maternal physiological changes in pregnancy / Musculoskeletal / Postural stability / Response to perturbations
caption_attribution_description: English: Adapted from: J.L. McCrory, Chambers, A.J., Daftary, A., Redfern, M.S., 2010. Dynamic postural stability during advancing pregnancy. Journal of Biomechanics. 43, 2434-2439.
context_page_description: Maternal physiological changes in pregnancy are the adaptations during pregnancy that the pregnant woman's body undergoes to accommodate the growing embryo or fetus. These physiologic changes are entirely normal, and include behavioral, cardiovascular, hematologic, metabolic, renal, posture, and respiratory changes. Increases in blood sugar, breathing, and cardiac output are all expected changes that allow a pregnant woman's body to facilitate the proper growth and development of the embryo or fetus during the pregnancy. The pregnant woman and the placenta also produce many other hormones that have a broad range of effects during the pregnancy.
context_section_description: Under dynamic postural stability, which can be defined as the response to anterior (front) and posterior (back) translation perturbations, the effects of pregnancy are different. Initial sway, total sway, and sway velocity (see figure for description of variables) are significantly less during the third trimester than during the second trimester and when compared to non-pregnant women. These biomechanical characteristics are possible reasons why falls are more prevalent during the second trimester during pregnancy.
  Additionally, the time it takes for pregnant women (any stage of pregnancy) to react to a translational disturbance is not significantly different than that of non-pregnant women. This alludes to some sort of stability mechanism that allow pregnant women to compensate for the changes they experience during pregnancy.
caption: As measured by a force platform, parameters used to measure postural stability. Adapted from McCrory et al. 2010
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