Infants Born to Women Who Were Affected by 9-11 Have Low Cortisol Levels.

Researchers measured the level of the stress hormone cortisol in the saliva of 38 women who were in or near the World Trade Center and pregnant at the time of the attack to determine if they had signs of PTSD. The infants born to women with low levels of cortisol had correspondingly low levels of the hormone, indicating that they also were vulnerable to PTSD.

Previous studies have shown corresponding low levels of cortisol in Holocaust survivors and their offspring, but researchers had attributed the association to "lifestyle factors," such as growing up with a parent who was depressed or anxious or hearing numerous stories about the Holocaust.

However, the infants of the women involved in the Sept. 11 attack were too young to understand or identify with their mother's anxiety, suggesting that "mechanisms for transgenerational transmission of biological effects of trauma may have to do with very early parent-child attachments and possibly even in utero effects," according to Yehuda. The researchers concluded, "The data suggest that the effects of maternal PTSD related to cortisol can be observed very early in the life of the offspring and underscore the relevance of in utero contributors to putative biological risk for PTSD."

The research on PTSD is part of a larger study Mount Sinai Hospital is conducting with Columbia University's Center for Children's Health that is tracking 200 women who were pregnant and near the World Trade Center when it was attacked.

This finding could be one more piece of the puzzle, explaining why some people are more vulnerable to acquiring PTSD than others who experience the same traumatizing events.