The odds of having a baby boy decreases after terrorist attacks, natural or man-made disasters, or economical depression. There are several studies worldwide that support this finding. This is somewhat counter-intuitive, because there are anecdotal accounts that report an increase in male births after a war, presumably to make up for the lost men.
Bruckner et al. (2010) wanted to see if this decrease in the odds of a male births, also called the secondary sex ratio, is due to a failure to conceive male babies or the male fetuses die in the womb before birth. They looked at the public databases from 1996-2002 fetal deaths and births from the U.S. National Center for Health Statistics.
The results showed that in the months following the September 11, 2001 terrorist attacks the deaths of male fetuses older that 20 weeks increased significantly. The authors make reference to the communal bereavement hypothesis, which stipulates that stress increases in persons not directly affected by a tragedy. Although the effects of stress on pregnant females is well documented, why the male fetuses seem to be more susceptible to mother’s stress is unknown.
I chose to feature this paper because of the recent Paris atrocities.
Reference: Bruckner TA, Catalano R, & Ahern J. (25 May 2010). Male fetal loss in the U.S. following the terrorist attacks of September 11, 2001. BMC Public Health.;10:273. doi: 10.1186/1471-2458-10-273. Article | FREE FULLTEXT PDF
By Neuronicus, 15 November 2015