(Hoping that I am posting this in the correct page)
Many years ago I was reading an old magazine (perhaps 30 years old or so) and in one of those trivia columns, I read about some hospital where many of its nurses got pregnant simultaneously.
Recently, a few years ago, I heard in the news a similar phenomenon: some nurses got pregnant almost simultaneously. Then I heard/read it again about another hospital, and again.
If you search for "nurses pregnant simultaneously" you will find several links to news articles. For example
https://www.today.com/parents/6-nurses-one-department-all-pregnant-same-time-t133529 From July 2018. This article speaks about 6 simultaneously pregnant nurses.
https://www.bbc.com/news/world-us-canada-45234247 From August 2018. 16 simultaneously pregnant nurses.
https://www.independent.co.uk/life-style/maine-medical-centre-pregnant-nurses-viral-photo-facebook-a8840406.html Most recent case, 9 simultaneously pregnant nurses.
In the same time, 7 firefighters from the same station got also pregnant almost simultaneously. https://www.charlotteobserver.com/news/local/article228478579.html
the news display these cases as some odd and cute "coincidence" without giving an explanation, but the odds are so high that can't be explained as a coincidence. Of course you can talk about coincidence if you refer to 2 persons getting pregnant simultaneously, but if we are talking about 6 or even 16 persons, we have to do with some phenomenon. And if this strange phenomenon is repeated, especially in the same workplace, we have to do with some trend.
Have such cases been obesrved or documented before, and can an explanation be given?