News Releases & Research Results New findings of Japanese women’s menstrual cycle and basal body temperature by big data analysis – Age-dependent significant changes in menstrual cycle and basal body temperature during the high-temperature phase -

2020.9.11News Releases & Research Results


The results of collaborative research conducted by Assistant Professor Takayuki Tatsumi of the Department of Perinatal and Women's Medicine, Tokyo Medical and Dental University, Director Satoshi Narumi of the Department of Molecular Endocrinology, Director Naho Morisaki of the Department of Social Medicine, and Researcher Makiko Sampei of the National Center for Child Health and Development, and MTI Ltd.

The key results of research are as follows:

  • Big data from 310,000 Japanese women and 6 million menstrual cycles were analyzed using a healthcare information service for women, Luna-Luna (MTI), demonstrating age-dependent changes in the menstrual cycle and basal body temperature.
  • The mean menstrual cycle is the longest at the age of 23, gradually decreases until the age of 45, and becomes longer again. The basal body temperature remains constant during the low-temperature phase regardless of age, but changes with age during the high-temperature phase, reaching the highest level in their thirties.
  • The results of research should facilitate the understanding of menstrual cycle and basal body temperature for women to consider the life stages of pregnancy, childbirth, and parenting.

This research project was conducted with the support of the Project for Whole Implementation to Support and Ensure the Female Life by AMED.

  • The results of research were published online in the international journal of obstetrics and gynecology Obstetrics & Gynecology on Sept. 10.


Tatsumi T., et al. Age-dependent and seasonal changes in menstrual cycle length and body temperature based on big data Obstetrics & Gynecology

Last updated 2020.9.11