Zoe Williams cites the American sociologist Elizabeth Armstrong, who “examined the evidence for the detrimental effects of stress on a pregnancy. The only demonstrable correlation was between a profound stress event – the death of an existing child, or spouse – during pregnancy, and a negative outcome” (The Handmaid’s Tale comes to life in Alabama, 2 July).

Several scientific studies have shown a significant effect on the offspring of pregnant women living in the area of catastrophic events, such as 9/11 and the earthquake in Kobe, Japan, in 1995. The ratio of boys to girls born alive a few months later is always reduced. The male foetus is more vulnerable than his female sister to death from severe maternal stress.

Conversely, when women are secure and optimistic they produce more boys than usual. ONS data of sex ratios at birth show three such peaks, in 1919, 1945 and 1974. All were times of hope and social cohesion, the first two at the end of world wars, and the third when social inequality in the UK (and in the rest of the western world) was at its lowest ever.

While the sex ratio was relatively high in the 30 years after 1945, it has settled since the mid-1980s at levels not seen since the 1930s.

Dr Sebastian Kraemer

London

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