Pregnant women who experience a lot of stress are more likely to have their daughters enter puberty early, according to a first-of-its-kind study.
The firstborn daughters of these stressed mothers were more likely to develop public hair, pimples and cognitive improvements than the daughters of relaxed women.
Researchers from the University of California – Los Angeles (UCLA) followed more than 250 mothers and their children for 15 years, starting during the first trimester of the mothers’ pregnancy.
The team measured the women’s stress, depression and anxiety levels during their pregnancy, but also shortly after giving birth.
They then followed the children at various points between the ages of eight and 16 to measure signs of puberty, including body hair, growth spurts, breast development, menstruation and facial hair growth.
The team found that the first signs of puberty – a series of symptoms caused by the ‘awakening’ of glands that release sex hormones – were present at an earlier age in first-born daughters.
However, this association was not seen in boys or girls who were not born first.
The researchers found that prenatal stress was linked to earlier signs of puberty in first-born girls, although there was no effect in boys
Early puberty in girls has been linked to several health problems later in life, including type 2 diabetes, depression and breast cancer
Dr. Molly Fox, lead author of the study and a biological anthropologist at UCLA, said: ‘This research adds to the body of knowledge in our field and demonstrates the significant and lifelong consequences for women and their offspring when it comes to prenatal emotional, environmental – and other factors. .’
‘This is important as we continue to develop practical and policy solutions that contribute to better access to healthcare and the overall well-being of pregnant mothers.’
The researchers recruited 253 pregnant women from two clinics in Southern California, starting when they were all in their first trimester.
The average age of the mothers was 30 years old, and all were pregnant with only one baby at a time. For about half of them, this was their first pregnancy.
About 45 percent of participants were white and 30 percent were Latina. Of the children born, 48 percent were women and 52 percent were men.
At 15, 19, 25, 31 and 37 weeks of pregnancy, researchers evaluated the mothers’ stress, depression and anxiety levels.
For example, they were asked to indicate to what extent they felt certain statements were true for them, such as ‘I felt lonely’. For anxiety measures, they were asked how often they felt certain symptoms, such as “nervous.”
As the children grew up, they were assessed at ages 8-10, 11-12, and 13-16. The team took saliva samples from each child to test the levels of hormones such as estrogen and testosterone produced by the adrenal glands and gonads, which signal puberty.
The adrenal glands are located on the kidneys, while the gonads are located near the reproductive organs – ovaries for girls and testes for boys.
Biomarkers the team measured included body hair, skin changes, height growth or growth spurts, breast development and menstruation in girls, and voice changes and facial hair growth in boys.
Additionally, researchers measured signs of childhood trauma or stress, such as the death of a parent, divorce, absence of a father figure and low income.
The team found that women who experienced high levels of stress during pregnancy were more likely to have first-born daughters who went through early puberty, although this was not seen in boys or girls who were not first-born.
No significant association was seen with regard to the age at which girls started menstruating.
“This is a unique find and fascinating to look at through an evolutionary lens,” said Dr. Fox.
A growing body of research shows that girls who start puberty at an earlier age may be at risk for health problems later in life.
For example, a 2023 study from Tulane University in Louisiana found that girls who started menstruating before age 13 were at greater risk of developing type 2 diabetes and stroke in adulthood than their peers who started menstruating later.
In addition, a study has been published in the journal Hormones and behavior found that girls who experienced early puberty were more likely to become depressed.
And an examination of the Lancet discovered that girls who had their periods at a young age had an increased risk of breast cancer.
The new research was published in the journal on Tuesday Psychoneuroendocrinology.