Maternal stress in the wake of the attacks might have led to selective miscarriage of male fetuses

The belief that a frightening experience during pregnancy can harm a woman’s unborn baby is one of the oldest of old wives’ tales. Genetic factors and prenatal exposure to alcohol, drugs, and other toxins are the primary causes of birth defects and miscarriages. But it also appears to be true that psychological stress during pregnancy caused by war, terrorism, mass shootings, natural disasters, or economic calamity can also cause the deaths of fetuses—especially if they’re male.

Normally, slightly more male babies are born than females. However, maternal stress lowers the male/female ratio of births in a population (the M/F ratio), and this is believed to be the result of selective miscarriage of male fetuses. A study published in 2015 found that the 9/11 attacks lowered the M/F ratio in the United States significantly a few months after the attack. The same phenomenon was observed previously in theaftermath of the assassination of John F. Kennedy in November, 1963. This finding was replicated in a study published last month, August, 2016, in the journal of Early Human Development by analyzing World Health Organization statistics.

Terrorist attacks in Northern Ireland, the Rodney King riots in April 1992, and the mass shootings by Anders Breivik in Norway in 2011, and in Sandy Hook in 2013 were all followed by a sharp and statistically significant drop in the M/F ratio at birth four to five months after each of these traumatic events. Fear in the aftermath of the Chernobyl nuclear reactor accident had a negative effect on male fetuses during the third month of prenatal development, resulting in a significantly lower M/F ratio of births in the Czech Republic. A drop in the M/F ratio in the United States also occurred after the Great Recession of 2007, presumably as a result of the economic stress the financial collapse caused families.

To read the complete article please see the original post on Scientific American:

http://blogs.scientificamerican.com/guest-blog/9-11-s-most-innocent-victims/