Dr Obel used a set of data collected between 1989 and 1992.

ECONOMIST: The sex of a child may depend on how stressed its mother is

Dr Obel found that the more stressed a mother had been, the less chance she had of having given birth to a boy.

ECONOMIST: The sex of a child may depend on how stressed its mother is

Dr Obel suspects the immediate cause is that male pregnancies are more likely to miscarry in response to stress than female pregnancies are, especially during the first three months.

ECONOMIST: The sex of a child may depend on how stressed its mother is