Stress in pregnancy is more likely to lead to the birth of a girl, a study found.
There is also a higher risk of premature birth among stressed mums-to-be. On average, around 105 males are born for every 100 females.
But among women experiencing physical and psychological stress, the chances of having a daughter rose to ratios of 4:9 and 2:3 respectively.
Results were compared with patterns seen after the 9/11 terror attacks when the number of newborn boys decreased.
Previous studies found males are more vulnerable to adverse prenatal environments.
Prof Catherine Monk, from New York’s Columbia University, said: “The womb is an influential first home.”
Physically stressed mums with high blood pressure and calorie intake are also more likely to give birth prematurely.
Their foetuses had lower heart rate and movement coupling, a sign of slower central nervous system development.
Prof Monk said: “Maternal mental health matters, not only for the mother but also her future child.”
Source: The Sun UK