A recent study found that birth defects among male infants fell below expected values after the terrorist attacks of September 11, 2001. The findings suggest that large and unexpected stress in pregnant women may have selected against weaker male fetuses, leading to fewer defects among newborn males.
For the study, investigators analyzed data from the California Birth Defects Monitoring Program from July 1985 to January 2004. The researchers included 6 birth defects that disproportionately affect males.
"This study adds to the evidence suggesting an excess loss of frail gestations following large population stressors, such as 9/11," said Dr. Tim Bruckner, senior author of the Birth Defects Research study.