A new study has shown that exposure to stress during the last three months of pregnancy can lead to a decrease in IQ levels among male children. According to the British newspaper "Daily Mail," when a woman is pregnant, her cortisol levels naturally increase, a steroid hormone released in response to stress, which is essential for the healthy growth of the child and positively impacts brain development. However, a team of researchers found that excessive cortisol levels during the last trimester of pregnancy might hinder the IQ scores of boys at the age of seven.
To examine its effect on cognitive function during childhood, researchers analyzed data related to cortisol levels in 943 pregnant women during the last three months of their pregnancy, along with IQ tests for their children at age seven. The researchers, presenting their findings at the European Endocrine Conference in Stockholm, discovered that pregnant women carrying a boy had lower cortisol levels in their blood compared to those carrying a girl. Boys exposed to higher levels of cortisol in the womb scored lower on IQ tests at age seven, while it appeared that girls were not affected.
Researchers from the University of Odense in Denmark indicated that their findings suggest boys may be "more susceptible to prenatal cortisol exposure" compared to girls. A previous study conducted by the same research team found that children aged one to three had more advanced verbal and language skills when their mothers had high cortisol levels during the third trimester of pregnancy. The results revealed that boys whose mothers were exposed to high stress levels could say more words at ages 12 to 37 months, while girls excelled in understanding more words at ages 12 to 21 months.
Dr. Anja Finger Dreyer, the lead researcher, stated, "Although the previous study showed that prenatal cortisol exposure was positively linked to language development, the new study links prenatal cortisol exposure negatively to IQ scores," explaining that the results mean "that high levels of prenatal exposure can have a temporary impact on the child's cognitive development." Separate research has also found that children exposed to high cortisol levels are more likely to face behavioral problems and stress-related illnesses later in life.
