Evaluation of planned number of children, the well-being of the couple and associated factors in a prospective cohort in Yokohama (HAMA study): study protocol

<jats:sec> <jats:title>Introduction</jats:title> <jats:p>Many developed countries including Japan are experiencing declining birth rates, particularly in urban areas. A gap between the planned number of children and the actual number of children exists, that is attributed to various factors such as: childcare leave and employment policies, childcare services, financial support, husbands’ contributions to household chores and childcare, marriage support, community, and couples’ well-being. Therefore, we propose HAMA study for having a baby, parenting, and marriage life (HAMA = ‘H’aving ‘A’ baby, parenting, and ‘MA’rriage life) in Yokohama (an urban area) to examine these issues.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods and analysis</jats:title> <jats:p>In this large-scale cohort study, we will elucidate the actual situation of families and child-rearing in Yokohama, evaluate the current policies and propose future measures to prevent a decline in the birth rate. Overall, 10 000 young married couples (wives aged 20–39 years as of 2022) will be randomly selected, and a survey form will be sent to them annually. They will be followed-up for 5 years to examine the factors associated with the planned number of children, well-being of the couple, childcare support policies, externalisation of housework and childcare, fathers’ participation in housework and childcare, wives’ free time, loneliness and social connectedness, relationship with the spouse and if they are working, questions regarding their work style and work-life balance will also be included. Ultimately, a conceptual model of the planned number of children and associated factors will be developed.</jats:p> </jats:sec> <jats:sec> <jats:title>Ethics and dissemination</jats:title> <jats:p>This study has been approved by the Ethics Committee of Yokohama City University (reference number: 2022–10) and will be conducted following appropriate ethical guidelines. Opportunities to withdraw consent to participate in the survey are provided to participants. The results of this survey will be published as research papers in relevant journals and will be reported to the administration of Yokohama city and other agencies.</jats:p> </jats:sec>