Study design
In this study, data from the Japan Environmental Children’s Study (JECS), a government-funded birth cohort study that started in January 2011, were used. This survey investigated the effect of several environmental factors on children’s health.19Eligibility requirements of JECS participants (mothers) were as follows: (1) living in the study area at the time of application and were expected to live in Japan in the near future; (2) expected delivery date was between August 1, 2011, and mid-2014; and (3) could participate without difficulty (i.e. they could answer the self-management questionnaire). Written informed consent was obtained from all participating women.
The JECS protocol was reviewed and approved by the Ministry of the Environment’s Institutional Review Board on Epidemiological Studies and by the Ethics Committees of all participating institutions. The JECS was conducted in accordance with the Helsinki Declaration and other nationally valid regulations and guidelines.