More stress, fewer boys

No one has yet been able to explain why, but several studies have suggested a drop in the rate of births of boys in the 3 to 5 months following a sociologically anxiety-provoking event. It looks like the pandemic will have to be added to the list.

Past studies have suggested this, among other places in New York after the attacks of September 11, 2001, in Great Britain after the death of Princess Diana and in Norway after the 2011 massacre. This is what led the psychologist Margaret Ryan, from Trinity College in Dublin, to look into the pandemic. In a pre-published study – therefore not peer-reviewed – she and her colleagues from three countries write that in March 2020, in England and Wales, there is a “significant drop in the ratio” of boys at birth, from 1054 per 1000 girls (which was the average between 2012 and 2020) to 1040 per 1000. This was the lowest ratio for a month of June in this period.

By December 2020, nine months after COVID-19 officially became a pandemic, the ratio was back to normal — though December 2020 also saw the lowest number of births of any month in 2012- 2020.

It should be noted that, if we do not know the reason for this drop, we also do not know why the ratio of boys is traditionally a little higher. Over the years, biologists have often referred to the fact that more boys die young, so this « surplus » would compensate. But if there is a biological mechanism, it has not been identified. Nor is the hypothetical mechanism that would explain that stress translates into fewer boys.

One of the tracks, as much for the « surplus » as for the « deficit » in anxiogenic period, is an unconscious mechanism which, in women, would push to a miscarriage when a future baby would have less chances of surviving in its future environment. . As boys are often more frail than girls at birth, this mechanism would put them at a disadvantage. But the idea remains purely speculative, for lack of evidence leading to this mechanism – and it is not for lack of having sought it.

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