The stress of the Sept. 11 attacks caused a dramatic increase in the number of miscarried pregnancies throughout the nation, a new study has found.
The data finds that 12% more male babies were lost in September 2001 after the 20th week of pregnancy than in a "normal" September.
Data found that ewer boys were born in all 50 states three to four months after 9/11.
The loss was attributed by researchers to "acute mental distress" related to a major national event, like 9/11, even if there is no direct connection to those who died or were involved in these events.
Dr Tim Bruckner, who led the research, explained that pregnant mothers are thought to be particularly prone to this experience. So too are unborn baby boys.
Bruckner and his colleagues used fetal death data from all 50 states compiled by the National Vital Statistics System between January 1996 and December 2002 to calculate how many male fetal losses would be expected in a normal September. Reviewing all fetal deaths occurring at or beyond the 20th week, they found male fetal losses spiked 3 percent above expected levels in September 2001.
"Across many species, stressful times reportedly reduce the male birth rate," said Bruckner, in explaining this phenomenon. "This is commonly thought to reflect some mechanism conserved by natural selection to improve the mother's overall reproductive success."