*4.5. Limitations*

There are still some limitations. The acute effect of the footwear conditions was investigated, and no conclusions can be drawn for longer-term or habituation effects. We only investigated the impact of three different heel-toe drops on gait parameters. The study sample will be expanded in the future, and electromyography (EMG) data will be included to infer further what mechanisms are involved in the generation and change of force. Future studies should explore the effects of long-term different heel-toe drops on gait in pregnant women in different periods and the longer-term effects.

#### **5. Conclusions**

This study compared the gait spatiotemporal parameters, GRF, and balance of pregnant women wearing different heel-toe drop shoes in the third trimester of pregnancy. The results are as follows: (1) NHS reduced the walking speed of women in the third trimester of pregnancy by reducing the stride. (2) The results showed that the impact of a heel-toe drop on the AP-GRF during the propulsion phase was relatively large, which might be due to the various dorsiflexion of the ankle with different heel-toe drop conditions. We inferred that changing heel-toe drop within a certain range does not change the ML stability of pregnant women in the third trimester of pregnancy. (3) We found that peak posterior COM-COP inclination angles are significantly smaller, so NHS may increase the stability of the pregnant women's propulsion phase and help women maintain balance in the third trimester of pregnancy. Understanding the gait differences in NHS, NS, and PHS of pregnant women in the third trimester will provide information for future research, evidence for the design of shoes for pregnant women, and falls prevention.

**Author Contributions:** Conceptualization, X.L. and Z.L.; methodology, R.X. and Y.G.; software, X.L. and Z.L.; validation; formal analysis, X.L. and D.S.; data curation, D.S. and Z.Z.; writing original draft preparation, X.L.; writing—review and editing, Z.L. and Z.Z. supervision, R.X. and Z.Z.; project administration, Y.G. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Key R&D Program of Zhejiang Province China (2021C03130), Zhejiang Province Science Fund for Distinguished Young Scholars (LR22A020002), Philosophy and Social Sciences Project of Zhejiang Province, China (22QNYC10ZD, 22NDQN223YB), Zhejiang Province Medical and Health Science and Technology Plan Project (2018KY710), Educational science planning project of Zhejiang Province (2021SCG083), Ningbo Public Welfare Science and Technology Plan Project (2019C50095), Public Welfare Science and Technology Project of Ningbo, China (2021S134), Basic scientific research Funds of provincial Ningbo University (SJWY2022014) and K.C. Wong Magna Fund in Ningbo University.

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Committee of Ningbo University (code RAGH20211106).

**Informed Consent Statement:** Written informed consent has been obtained from the participants to publish this paper.

**Data Availability Statement:** The data that support the findings of this study are available on reasonable request from the corresponding author. The data is not publicly available due to privacy or ethical restrictions.

**Conflicts of Interest:** The authors declare no conflict of interest.
