MAY 13, 2024 2:03 PM PDT

Higher Cortisol in Pregnancy Linked to Lower IQ in Boys, not Girls

WRITTEN BY: Annie Lennon

Higher levels of cortisol in the third trimester of pregnancy are linked to lower IQ scores in 7-year-old boys, but not their female peers. Meanwhile, higher cortisone levels in urine during pregnancy are linked to higher IQ scores in girls. The corresponding study will be presented at  the 26th European Congress of Endocrinology. 

Cortisol is a steroid hormone that is commonly known for its role in the stress response. Prenatal exposure to the hormone is necessary for fetal development and may affect cognitive function later on. 

Meanwhile, cortisone is an inactive form of cortisol. An enzyme called 11β-hydroxysteroid-dehydrogenase type 2 (11β-HSD2) in the placenta regulates how much cortisol reaches growing fetuses by converting cortisol into cortisone. 

In previous work, researchers at the Odense University Hospital in Denmark found that children born to mothers with high cortisol levels during their third trimester have more advanced speech and language skills between the ages of one and three.

In the current study, the same researchers investigated the effects of cortisol and cortisone exposure in the womb on childhood IQ test results. To do so, they examined data from 943 pregnant women in their third trimester alongside IQ test results from their children when they reached 7 years old. 

Ultimately, they found that pregnant women carrying boys had lower blood cortisol levels than women carrying girls. They further found that boys exposed to higher levels of cortisol in the womb scored lower on IQ tests at 7 years old. Meanwhile, 7-year-old girls scored higher on IQ tests when their mothers had more cortisone in their urine. 

Lead author of the study, Dr Anja Fenger Dreyer, said in a press release: “Our results show that girls may be more protected by the activity of placental 11β-HSD2, whereas boys may be more vulnerable to prenatal exposure of maternal physiological cortisol.”

“Although our previous study showed prenatal cortisol exposure was positively associated with language development, in this study prenatal cortisol exposure- ‘directly’ by serum cortisol and ‘indirectly’ by urine cortisone- is negatively associated with IQ scores,” she continued.

“This may mean that the high levels of prenatal cortisol exposure might have a temporary effect on a child’s cognitive development. It should also be noted that the vocabulary in toddlers was reported by parents in our previous study, while child IQ in this study was assessed by trained psychologists,” she concluded. 

Sources: Neuroscience News, New York Post

About the Author
Bachelor's (BA/BS/Other)
Annie Lennon is a writer whose work also appears in Medical News Today, Psych Central, Psychology Today, and other outlets.
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