Differences in trunk control between early and late pregnancy during gait

• We explored the differences in the functional ability of the trunk during gait between before and during 3rd trimester of pregnancy.
• Pregnant women during 3rd trimester of pregnancy will decline in the functional ability of the trunk in anteroposterior direction, not but mediolateral direction, during gait.
• The decline in the functional ability of the trunk during gait might be associated with low back pain during pregnancy.

The aim of this study was to compare gait characteristics, including the functional ability of the trunk, between women before and during the third trimester of pregnancy. Gait measurements were performed on 27 pregnant women, who were divided into two groups using the threshold of 28 gestational weeks. The subjects were instructed to walk at their preferred speed. In addition to stride-time coefficient of variation, root mean square (RMS) and autocorrelation coefficient, coefficient of attenuation (CoA) of acceleration was computed as an index to assess the functional ability of the trunk. Differences of gait characteristics between the groups were determined by the Mann–Whitney U test. Gait characteristics that showed a significant difference between the groups were further analyzed with adjustment by age, height, weight and gait velocity by using multiple regression analysis. Women during the third trimester of pregnancy showed significantly smaller RMS in the anteroposterior direction at the lower trunk than those before the third trimester of pregnancy, even after adjusting for age, height, weight and gait velocity [β = 0.47; 95% confidence interval (CI) 0.07–0.25]. CoA in the anteroposterior direction was also significantly lower in women during the third trimester of pregnancy than in those before the third trimester of pregnancy after adjustment by age, height, weight and gait velocity (β = 0.44; 95% CI 0.39–18.52). The present cross-sectional study suggests the possibility that the functional ability of the trunk during gait declines in late pregnancy.