*4.1. Gait Spatiotemporal Parameters*

Gait parameters changed with different heel heights of shoes [41]. Although studies have shown that 2/3 of falls during pregnancy occur due to smooth surfaces, sudden acceleration, or moving objects [6,8], gait changes caused by pregnancy are still one of the critical causes of falls in pregnant women [16]. Therefore, it is necessary to understand the influence of shoes with different heels on the gait spatiotemporal parameters of pregnant women in the third trimester.

This study found that participants wearing NHS showed decreased stride length and speed compared to PHS. Similar to our results, Benz (1998) reported that the NHS's walking speed was significantly reduced due to a shorter stride length combined with an increased cadence [42]. Li et al. reported that walking with NHSs induced the upper body to tilt backward, which may have caused a disadvantage in the propulsion phase compared to walking with normal shoes [41]. This may be the reason for the decrease in stride length. PHS moved the center of gravity forward, and the forward tilt of the trunk assisted in moving the center of gravity outside the support area. There is more motivation during the duration of take-off [43,44], which may be the reason for the difference in stride length between NHS and PHS. Previous studies found that the habitual gait in the third trimester of pregnancy is characterized by slower speed and shorter step length, which may be caused by slow gait strategies [16]. Taking a shorter step during pregnancy reduced the gait's energy consumption and increased the gait's stability [16]. This change in stride length and speed may lead to changes in other gait parameters and may help increase gait stability in pregnant women. On the other hand, the decreased stride length may be due to unfamiliarity with NHS, which leads to anxiety about falls and a more conservative or unstable gait [16,45–47].
