2.1. Study Design
We conducted a randomized, double-blind, placebo-controlled, parallel-group trial from 19 March 2021 to 19 August 2021 at the Chiyoda Paramedical Care Clinic (Tokyo). The study protocol was approved by the Institutional Review Board of Chiyoda Paramedical Care Clinic (approval No. 21031902, Tokyo) and the Meiji Institutional Review Board (Tokyo) (approval No. 197) and was designed to comply with the Declaration of Helsinki. The protocol was also registered in the UMIN Clinical Trials Registry (UMIN000043966). Participants were recruited via the website of CPCC Co., Ltd. (Tokyo, Japan). Each woman provided written informed consent to participate before randomization. A data-monitoring committee assured us of the accuracy of data collection and inputs. All of the study procedures, including its explanation, written informed consent acquisition, questionnaire, and testing, were conducted in Japanese. The reporting of this trial follows the recommendations of the CONSORT (Consolidated Standards of Reporting Trials) 2010 statement [