The Japan Nurses’ Health Study (JNHS) is a prospective cohort investigation of the effects of lifestyle and healthcare on women’s health.
The primary purposes of the JNHS are to describe the status of lifestyle, healthcare practice, and physical status of Japanese women, to estimate the effects of those factors on their health, and to establish evidence regarding the risk-benefits of long-term administration of women-specific health management such as exogenous hormones use.

The study was initiated in 2001 with a six-year entry period and a twenty-year follow-up.
The study population comprises female registered nurses, licensed practical nurses, public health nurses, and midwives, aged 25 years or more at baseline survey.
The participants were recruited in cooperation with the Japan Menopause Society and the Japanese Nursing Association.

We sent a self-administered baseline questionnaire that solicited demographic information, lifestyle, pharmaceutical drug use, physical condition, reproductive health, and disease history, with a list of photographs of female hormone drugs.
The baseline survey was completed in 2007, and 49,997 women responded from all 47 prefectures of Japan.
Among the respondents, approximately 15,000 women who agreed to be followed-up returned signed informed consent sheets with completed baseline questionnaires. Changes in lifestyle, healthcare, incidence of disease, and health outcome over time will be studied.
The cohort receives annual JNHS newsletters and biennial follow-up questionnaires by mail.