Early puberty in first-born daughters linked to high stress during mother's pregnancy

New Delhi: Early signs of puberty in first-born daughters could be associated with high stress levels their mothers experienced while pregnant, new research has found.

Researchers said that they examined adrenal puberty, which is marked by changes like the growth of body hair, pimples and aspects of cognitive maturation, but does not include breast development or the onset of menstruation in girls or testicular enlargement in boys.

The team of researchers, led by the University of California, Los Angeles (UCLA), US, said they did not find these correlations between stress levels during pregnancy and early maturation signs in both boys and daughters who were not first-born.

They said the findings are important for practical and policy solutions that contribute to greater access to healthcare and the general wellbeing of pregnant mothers.

"This research adds to the body of knowledge in our field showing the significant and lifelong impacts to women and their offspring when it comes to prenatal emotional, environmental and other factors," said anthropologist Molly Fox, UCLA, and lead author of the study published in the journal Psychoneuroendocrinology.

For the study, the researchers recruited 253 mother-child duos from two obstetric clinics in Southern California during routine first trimester prenatal care visits. The mothers were 30 years old on average and experiencing single-child pregnancies, they said, with about half of them being pregnant for the first time.

The researchers measured the women's stress, depression and anxiety levels at 15-, 19-, 25-, 31- and 37-weeks' gestation to create a prenatal psychological distress composite score. They also assessed a postnatal distress composite score by measuring these levels two to three months following childbirth.

Following up on the children for over 15 years, the team measured their biomarkers of adrenal and gonadal puberty separately at ages 8-10, 11-12 and 13-16. The biomarkers included body hair, skin changes, growth in height or growth spurts, breast development and the onset of menstruation (in girls), voice changes and facial hair growth (in boys).

The children's saliva samples were used for evaluating hormone levels which are indicators of adrenal and gonadal puberty, the team said.

The researchers also assessed childhood adversity such as a parent's death or parents separating before age 5 to account for other factors known to be linked to early maturation or signs of puberty in children and adolescents.

The results had implications for the field of fetal programming, or studies exploring the impact of stress and other factors affecting pregnant women on foetuses and children long after their birth, the team said.

"This is a first-of-its-kind finding and is fascinating to look at through an evolutionary lens," said Fox.