Gender and environment: general and monthly gender distribution of newborns and cosmophysical parameters

Abstract

Recent publications have described a relationship between fluctuations in environmental physical activity and several aspects of fetal development. This study explored the possible effects of cosmophysical parameters on newborn gender, overall and by maternal age. The gender distribution of 123,368 infants born over a 189-month period (November 1993–July 2009) was analyzed against levels of solar, geomagnetic, and cosmic ray activity at the time of conception. The cohort was then divided into three groups by maternal age (< 28 years, 29-35 years, > 35 years) for further analysis. Pearson correlation coefficients and their probabilities were calculated, and chi-square test was applied, as necessary. The physical data were derived from space science centers in the USA, Russia, and Finland. The results showed that the male/female ratio for the whole cohort over the study period was 1.06. However, on monthly analysis, there was a significant male predominance in most months, with a male/female ratio of up to 4. Younger mothers (< 28 years) gave birth to significantly more boys than older mothers. The gender distribution in the three maternal age groups was partially linked to the different physical factors. These findings suggest that environmental physical activity in the month of conception may play a role in newborn gender. Further study is needed to determine the mechanism underlying this effect.