Women who experience more stress during conception are twice as likely to give birth to a GIRL, the study finds
- Experts monitored the stress level in 108 women before conception until birth
- They did this by measuring the stress hormone cortisol in hair samples
- Women who continued to give birth to girls had higher cortisol levels around conception
- The results confirm how fetuses are vulnerable to the impact of maternal stress
One study found that women are twice as likely to give birth to a girl if they experienced more stress during conception.
Researchers in Spain recorded the levels of the stress hormone cortisol in the hair of 108 women around the ninth week of pregnancy until birth.
Each hair measurement covered cortisol levels for the last three months – meaning that the first one taken covered the previous period and including conception.
The findings confirm that fetuses are vulnerable to the effects of maternal stress and that they may play a key role in their development.
One study found that women are twice as likely to give birth to a girl if they experienced more stress during conception. Pictured: a newborn baby girl
“The results we found were surprising,” said the author and psychologist of the paper, María Isabel Peralta-Ramírez, from the University of Granada.
“They showed that women who gave birth to girls had higher levels of cortisol in their hair in the previous weeks, during and after conception than those who had boys.”
The findings add to growing evidence that the stress experienced by mothers during conception and during pregnancy can have an impact on the nature of the baby’s pregnancy, birth and even neurodevelopment.
“Our research group has shown in numerous publications that psychological stress in the mother generates a greater number of psychopathological symptoms during pregnancy,” said Professor Peralta-Ramirez.
Stress, she added, can also trigger “postpartum depression, a higher probability of assisted birth, an increase in the time needed to start breastfeeding or lower neurodevelopment of the baby six months after birth.”
This study, the team explained, is one of the few that showed the impact of stress felt during and even before conception – rather than just the psychological stress experienced during pregnancy.
The findings add to growing evidence that the stress experienced by mothers during conception and during pregnancy can have an impact on the nature of the baby’s pregnancy, birth and even neurodevelopment. In the picture: a young woman is stressed
According to the researchers, it is possible that their findings can be explained by the body’s “stress system” changing the concentration of sex hormones at conception, but how exactly this would work is not clear.
There is evidence that testosterone could influence a baby’s sex – and the higher the prenatal stress levels, the higher the female testosterone levels.
Alternatively, the team explained, there is also evidence that sperm carrying the X chromosome – and therefore the ability to conceive a female fetus – are better able to pass through cervical mucus in adverse circumstances.
“There are other possible hypotheses that try to explain this phenomenon,” said Professor Peralta-Ramirez.
“Among the strongest theories is the idea that there are several interruptions of male fetuses for medical reasons in the first weeks of pregnancy in situations of severe maternal stress,” she added.
“That being said, given the design of these studies, it is recommended that the results be corroborated in depth.”
The full results of the study were published in the Journal of the Origins of Health and Disease Development.