Archives of gynecology

, Volume 233, Issue 4, pp 263–266

A study of the sex ratio of first-born According to the mother's month of birth

  • T. Miura
  • K. Nonaka
  • M. Shimura
  • I. Nakamura
Original Papers

DOI: 10.1007/BF02133800

Cite this article as:
Miura, T., Nonaka, K., Shimura, M. et al. Arch. Gynecol. (1983) 233: 263. doi:10.1007/BF02133800

Summary

The male-to-female sex ratio at birth of the first-born babies delivered in Japan to mothers aged 25 years or less was investigated in two groups: a hospital group and a questionnaire group. The sex ratio fluctuated according to their mother's month of birth. Between 1924 and 1928, the sex ratio of the offspring of the mothers born in March-May in both groups was significantly higher than that of the other mothers. We speculate about the relationship between the sex ratio at birth and the mother's month of birth.

Key words

EpidemiologyMonth of birthSex ratio

Copyright information

© J. F. Bergmann Verlag GmbH & Co KG 1983

Authors and Affiliations

  • T. Miura
    • 1
  • K. Nonaka
    • 1
  • M. Shimura
    • 1
  • I. Nakamura
    • 1
  1. 1.Dept. of HygieneTeikyo University School of MedicineTokyo 173Japan