Women are twice as likely to give birth to a girl if they experienced more stress around the time of conception, a study has found.
Researchers from Spain recorded the levels of the stress hormone cortisol in the hair of 108 women from around week nine of their pregnancy through to delivery.
Each hair measurement covered the cortisol levels for the preceding three months meaning the first one taken covered the period prior to and including conception.
The findings confirm that foetuses are vulnerable to the effects of maternal stress and that such can play a key role in their development.