Pregnant women who suffer high levels of stress are more likely to have daughters who reach puberty early, a first-of-its-kind study suggests.
The first-born daughters of these uptight mothers developed pubic hair, pimples, and cognitive improvements earlier than those born to relaxed women.
Researchers at the University of California – Los Angeles (UCLA) followed more than 250 mothers and their children for 15 years, beginning during the mothers’ first trimester of pregnancy.
The team measured the women’s stress, depression and anxiety levels during pregnancy, as well as once shortly after giving birth.
They then followed the children at various times between ages 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 set of symptoms triggered by the “awakening” of glands that release sex hormones) were present at an earlier age in first-born daughters.
However, this link was not observed 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 that shows the significant and permanent impacts for women and their children when it comes to factors emotional, environmental and other prenatal conditions. .’
“This is important as we continue to find practical and policy solutions that contribute to greater access to health care and the overall well-being of pregnant mothers.”
The researchers recruited 253 pregnant women from two clinics in Southern California when they were all in their first trimester.
The average age of the mothers was 30 years old and they were all pregnant with a single baby at a time. For about half of them, this was their first pregnancy.
About 45 percent of the participants were white and 30 percent were Latina. Of the children born, 48 percent were female and 52 percent were male.
At 15, 19, 25, 31 and 37 weeks of pregnancy, the researchers assessed the mothers’ levels of stress, depression and anxiety.
For example, they were asked to rate the extent to which they felt certain statements were true for them, such as “I felt lonely.” To measure anxiety, they were asked how often they felt particular symptoms such as “nervousness.”
As the children grew, they were tested at ages 8 to 10, ages 11 to 12, and ages 13 to 16. The team took saliva samples from each boy to analyze the levels of hormones such as estrogen and testosterone produced by their adrenal and gonadal glands, which signal puberty.
The adrenal glands are located in the kidneys, while the gonadal glands are located near the reproductive organs: the ovaries in girls and the testicles in boys.
The 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, the researchers measured signs of childhood trauma or stress, such as the death of a parent, divorce, the 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 experienced early puberty, although this was not observed in boys or girls who were not born first.
No significant link was observed with respect to the age at which girls began menstruating.
“This is a first-of-its-kind finding and it’s fascinating to look at it through an evolutionary lens,” said Dr. Fox.
A growing body of research suggests that girls who go through puberty at younger ages 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 their periods before age 13 had a higher risk of developing type 2 diabetes and suffering strokes in adulthood than their peers who started. menstruate later.
Furthermore, a study published in the journal Hormones and behavior found that girls who went through early puberty were more likely to suffer from depression.
And a study of Lancet It found that girls who started their periods at an early age had a higher risk of breast cancer.
The new research was published Tuesday in the journal Psychoneuroendocrinology.