Women who experience more stress around conception are twice as likely to give birth to a GIRL, study finds
- Experts tracked stress levels in 108 women from before conception to birth
- They did this by measuring the stress hormone cortisol in hair samples
- Women who continued with girls had higher cortisol levels around conception
- The results confirm that fetuses are vulnerable to the impact of maternal stress
Women are twice as likely to give birth to a girl if they experienced more stress during conception, a study found.
Researchers from Spain recorded levels of the stress hormone cortisol in the hair of 108 women from approximately the ninth week of their pregnancy until delivery.
Each hair measurement related to the cortisol levels for the previous three months – meaning the first measurement related to the period prior to and including conception.
The findings confirm that fetuses are vulnerable to the effects of maternal stress and that these may play a key role in their development.
Women are twice as likely to give birth to a girl if they experienced more stress during conception, a study found. Pictured: a newborn baby girl
“The results we found were surprising,” says author and psychologist María Isabel Peralta-Ramírez from the University of Granada.
“They showed that the women who gave birth to girls in the weeks before, during and after conception showed higher concentrations of hair cortisol than those who gave birth to boys.”
The findings complement the growing evidence that stress experienced by mothers around conception and during pregnancy can have an impact on the nature of the pregnancy, birth and even the neurological development of the child.
“Our research group has shown in numerous publications how psychological stress in the mother during pregnancy generates a higher number of psychopathological symptoms,” says Professor Peralta-Ramírez.
Stress, she added, can also lead to “postpartum depression, a greater likelihood of assisted delivery, a longer time to breastfeed, or inferior neurological development of the baby six months after birth.”
This study, the team explained, is one of the few that has demonstrated the impact of stress during and even before conception – rather than just the psychological stress experienced during pregnancy.
The findings complement the growing evidence that stress experienced by mothers around conception and during pregnancy can have an impact on the nature of the pregnancy, birth and even the neurological development of the child. Pictured: a young woman is experiencing stress
According to the researchers, it is possible that their findings could be explained by the body’s ‘stress system’ altering the concentration of sex hormones at the time of conception, but exactly how this would work is not clear.
There is some evidence that testosterone could affect the sex determination of the baby – and the higher the prenatal stress, the higher the amount of female testosterone.
Alternatively, the team explained, there is also evidence that sperm carrying the X chromosome – and thus the ability to conceive a female fetus – are better able to pass through the cervical mucus in conditions of adversity.
“There are other possible hypotheses that try to explain this phenomenon,” explains Professor Peralta-Ramírez.
“One of the strongest theories is the idea that there are more medical terminations of male fetuses during the early weeks of pregnancy in situations of severe maternal stress,” she added.
‘That said, in the light of the design of these studies, it is advisable to further substantiate the results.’
The full findings of the study are published in the Journal of Developmental Origins of Health and Disease.