Geophysical variables and behavior: LXXXVI. Geomagnetic activity as a partial parturitional trigger--are male babies more affected than female babies?

The birth dates of 163 men and 245 women who were born between the years 1958 and 1969 were extracted from our data base for first-year university students. Daily aa values, measures of the amplitude of global geomagnetic activity, were obtained for the birthdays and for each of the seven days before and after the birthdays. Analyses of variance indicated no significant differences in the magnitudes of the geomagnetic activity during these 15 days; however, men were born when the geomagnetic activity was significantly higher than when the women were born. The effect, which was equivalent to a correlation coefficient of about .20, was largest for the day of birth and for the two or three days before birth. The means of the aa values for the day of birth and the day before birth for the men were about 7 nanoTesla higher than the values for the women.