Moms with high stress hormone levels are less likely to give birth to baby boys, says study.
Moms with high stress hormone levels are less likely to give birth to baby boys, says study.
GRANADA, Spain — Women suffering from stress before they become pregnant and during conception are almost twice as likely to give birth to a girl than a boy, according to a new study from researchers at the University of Granada in Spain.
The researchers analyzed cortisol levels in pregnant women’s hair. Cortisol is a steroid hormone that is released as a result of stress.
The 108 women who were part of the study had a sample of their hair taken, so they could assess their cortisol levels, according to Professor Maria Isabel Peralta Ramirez, 49.
“Hair accumulates the level of cortisol in that organism,” Peralta Ramirez, who is the main author of the study, said. “And, as hair grows one centimeter per month, if you take three centimeters, you have the cortisol levels belonging to before conception, during conception, and for the first weeks of the pregnancy.”
The women had the sample taken between the seventh and eighth week of their pregnancies. The research was conducted by three departments of the university — Mind, Brain and Behavior Investigation Center (Centro de Investigacion Mente, Cerebro y Comportamiento), the Department of Pharmacology, and the Psychology Faculty.
The women were monitored during their pregnancies and births and, according to Peralta Ramirez, “mums who had given birth to girls had higher — even double — the levels of cortisol than the ones having boys.”
“Previous research has stated that women facing extraordinarily stressful events had more girls,” she said. “But this research has gone deeper into the mechanisms that cause this.”
“There are three different types of stressful situations,” Peralta Ramirez said. “The extraordinary ones, which are shocking events like a car crash, the death of a loved one, or a traumatic event. Then there is the quotidian stress, which is smaller things, like work stress, traffic jams, not being able to pay bills at the end of the month, among other things.
“The last type of stress is called kept chronic stress, which is similar to the extraordinarily stressful situations, but it is kept for longer, like the ones suffered by doctors working in the emergency departments dealing with people who have the coronavirus, for example.”
“The bodies of women suffering from quotidian or daily stress, when they are pregnant, reduce their estrogen levels, which causes a hostile cervical mucus,” Peralta Ramirez said.
She explained that “cervical mucus is the discharge that allows the sperm to go to the ovule, and this mucus becomes acidic, so it becomes hostile and the sperm cannot arrive at the ovule properly.”
According to the professor, sperm with the X chromosome, which creates a female embryo, is more resistant to hostile cervical mucus caused by the stress effect, but sperm with the Y chromosome, which is destined to create male embryos, are faster but “weaker and more vulnerable”.
Peralta Ramirez also said that when women suffer from extraordinary stressful events, such as terror attacks or even when employees at their company are fired en masse, there is an increase in miscarriages that affects male fetuses more than female ones.
“It is as if nature, in these moments of adversity, is guaranteeing the survival of the species, because men can fertilize a lot of women, but if we are in a war period, nature needs more women,” she said.
The hormonal imbalance caused by stress cannot be cured with medicine, Peralta Ramirez said, as there is a “waterfall of hormones that affect fertilization”.
The team’s research has also confirmed that women with high levels of stress tend to have more psychopathological symptoms, such as depression and anxiety. “They are more vulnerable to developing postpartum depression, and it is more likely that the birth will end up being a cesarean or a manipulated birth, which is not a natural birth,” Peralta Ramirez said.
Stress levels during the last three months of pregnancy could also lead to other consequences, such as having problems making milk to breastfeed the newborn.
The coronavirus situation is making the already stressful situation of being pregnant worse. “The health care system in Spain does not have psychological support as a primary focus,” she said. “So, the women have to deal with the stress by themselves.”
To deal with this situation, she recommended finding psychological support and engaging in calming activities such as yoga or meditation.
The team of scientists is also studying whether more girls than boys are being born during the coronavirus pandemic.
(Edited by Vaibhav Vishwanath Pawar and Gaurab Dasgupta)
