Sex ratios at birth and environmental temperatures

Naturwissenschaften. 1999 Jul;86(7):340-2. doi: 10.1007/s001140050630.


The relationship between average monthly air temperature and sex ratios at birth (SRB) was analyzed for children born in Germany during the period 1946-1995. Both the absolute temperature and--more markedly--the monthly temperature deviations from the overall mean were significantly positively correlated with the SRB (P < 0.01) when temperatures were time-lagged against the SRB data by -10 or -11 months. It is concluded that the sex of the offspring is partially determined by environmental temperatures prior to conception.

MeSH terms

  • Female
  • Fertilization / physiology*
  • Germany
  • Humans
  • Infant, Newborn*
  • Male
  • Regression Analysis
  • Seasons*
  • Sex Ratio*
  • Temperature*