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The 2016 US Election May Have Changed Birth Sex Ratios In Canada


Stephen Luntz

Stephen has a science degree with a major in physics, an arts degree with majors in English Literature and History and Philosophy of Science and a Graduate Diploma in Science Communication.

Freelance Writer

canadian children

You need a large sample to notice, but slightly fewer boys were born compared to girls in Ontario in early 2017. The reason appears to have been shock at the US presidential result. Anna Kraynova/Shutterstock

The 2016 election had some unexpected effects in surprising places. Rising to the top of that list is the possibility of a reduced number of boys born in parts of Canada.

Disastrous events such as wars or famines can alter the proportion of male and female babies born in the years thereafter. The shift is small but can easily be detected when millions of births are involved, such as during both world wars. Even events that do not affect mothers directly can have an impact – fewer boys than normal were born in the USA shortly after 9/11, or in Norway after the 2011 far right massacre


Dr Ravi Retnakaran and Dr Chang Ye of Mount Sinai Hospital, Toronto, wondered if election results could do the same thing. Naturally, this would be harder to detect – a whole nation is traumatized by terrorism, but elections make about as many people happy as sad.

On the other hand, other countries are sometimes fairly united in who they want to win their neighbors' elections. American elections transfix the world, and polling companies sometimes ask the voters of other nations who they would vote for if they could. Canadians consistently indicate an overwhelming preference for Democrats over Republicans, including at the 2016 presidential election. Consequently, Retnakaran and Ye looked at the numbers of boys and girls born in Ontario before and after the election.

In BMJ Open, they report a sharp dip in the proportion of boys born in March 2017, which slowly returned to normal in the following months.

Effects usually show up 3-5 months after tragedies, but because there could have been many other explanations, the authors drilled down further into the data. Left-leaning parts of Ontario saw an even larger shift than the provincial average. More conservative areas had no change at all. Even many conservative Canadians preferred Hillary Clinton to Donald Trump, but it is to be expected they were less distressed by the result than their counterparts who support the (Canadian) Liberals, NDP, or Greens.


Although the full reason bad news affects birth ratios remains debated, male fetuses are known to be more susceptible to maternal stress than female ones. Considerably more boys than girls are conceived, but a higher rate of miscarriages brings the ratio closer to balance at birth. Anything that causes a spike in pre-term deaths will therefore show up in the sex ratios, given a sufficiently large sample. The effect can even be seen in seasonal data, with hot summers or cold winters having a small but noticeable impact.

The authors acknowledge that without knowing the politics of individual expectant mothers, they can't be certain the election, rather than some other event around the same time, caused the effect they measured, but the timing and distribution are striking.

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