According to a new study that is due to be reported at the American Society for Reproductive Medicine conference in Orlando, women who have higher levels of the stress hormone cortisol in the months leading up to conception are more likely to have a baby girl.
Researchers at the University of Oxford examined the lives of 338 women in the UK who were trying to conceive, they were asked to keep diaries on their day-to-day activities, sex lives and relationships. Participants were also surveyed on their stress levels and on the 6th day of their monthly cycle levels of cortisol within the body were measured up to the point of conception.
During the study, 207 women fell pregnant . The sexes of the babies born were said by the researchers to have a strong female excess with 72 girls and 58 boys. The statistical analysis of the results proved that the difference in the number or male and female babies born was not significant overall. However, of the women with the highest cortisol levels, they were 75 percent less likely to have a boy.
This is not the first time external pressures and stressors have been investigated to establish their influence on sex ratios at birth. Previously environmental factors, such as natural disasters and stress inducing situations such as war, have been found to alter the birth sex ratio.
More research needs to be conducted to establish the exact influence stress has on conception and sex determination of babies.