Recruitment and randomization
RECRUITMENT
Recruitment occurred at obstetric clinics and via a web survey monitor from August 2020 to July 2021, and follow-up was conducted until November 2021. The clinics were recruited at five locations in Tokyo or its suburbs, and the web-based survey monitors were recruited in Japan. The study content was presented to potential participants in writing, and those who were interested in the study were asked to complete the GAD-7. Participants who met the eligibility criteria and did not meet any of the exclusion criteria received another explanation about the study in writing and their consent was obtained. At this point, study IDs were assigned and a corresponding table was prepared. Random allocation software was used to perform stratified block random assignment of primipara and multipara participants with a block size of 4. Because of the computer-based software allocation, concealment was ensured. The study was not blinded to participants, interveners, or evaluators.