A girl takes photograph during the Tanabata festival at the Hatamono shrine in Osaka, Japan. A new study shows there was a spike in the birth of girls in Japan after the 2011 earthquake.
A number of studies already claim that large-scale disasters lead to more babies.
Now, it looks like girls outnumber boys in those circumstances.
Related: Japan’s huge Tohoku quake was even ‘heard’ in space
A study published in the Journal of Human Biology shows that fewer boys than girls were born in the months following the 2011 Tohoku earthquake, which devastated northern Japan.
Researchers at UC Berkeley found that there was a decline in male births following the earthquake in the districts nearest the Tohoku region. But districts farther away from the epicenter did not see a significant change, the study found.
So what’s the reason behind this gender skew?
The study points to a hormone called human chorionic gonadotropin, which helps protect a growing fetus from the mother’s immune system. Weak male fetuses make less of this hormone, thus making them more susceptible to miscarriage.
According to research by William James of University College London, the father’s testosterone levels could also be responsible for skewed sex ratios. Men tend to produce less testosterone during stressful times, James says, which could affect the number and quality of sperm that carry Y chromosomes.
Related: Royal Baby: Giving birth in the UK versus the US
Whatever the reason, as the Japan Daily Press points out: “The next generation of Japanese, at least in the Tohoku region, might just very well be the ‘girls’ generation.'”
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