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Preschool boys’ behaviors traced back to moms’ thyroid hormones



Pregnant women’s thyroid hormone trajectories (levels in the first, second, and third trimester) may predict whether their male offspring are aggressive or withdrawn at age 4.

Certain maternal thyroid hormone trajectories were associated with problem behaviors in preschool boys in a study of close to 2,000 mother-child pairs in China.

The researchers identified low, moderate, and high thyroid-stimulating hormone (TSH) and free thyroxine (FT4) trajectories.

A pregnant woman shironosov/Getty Images

Most women had a low TSH trajectory and moderate FT4 trajectory, which the researchers deemed to be reference (normal) trajectories.

The children’s primary caregiver (parent or grandparent) completed an extensive questionnaire about their child’s behavior at age 4.

The 4-year-old boys whose mothers had a high TSH trajectory during pregnancy were more likely to be withdrawn and to externalize problems (odds ratio, 2.01 and 2.69, respectively).

Boys whose mothers had a high FT4 trajectory during pregnancy were more likely to be anxious/depressed (OR, 2.22).

And boys whose mothers had a moderate TSH trajectory or low FT4 trajectory were more likely to show aggressive behavior (OR, 3.76 and 4.17, respectively), compared with boys whose mothers had normal TSH and FT4 trajectories, after adjusting for potential confounders.

However, there was no association between abnormal maternal thyroid hormone trajectories and behavior problems in 4-year-old girls.

The study by Peixuan Li, BM, and colleagues was published online Jan. 6 in the Journal of Clinical Endocrinology & Metabolism.

‘Study supports monitoring thyroid function in pregnancy’

“Our findings highlight the significance of close monitoring and management of maternal thyroid function during pregnancy,” senior author Kun Huang, PhD, said in a press release from the Endocrine Society.

“This research presents a new perspective in early intervention of children’s emotional and behavioral problems,” added Dr. Huang, from Anhui Medical University, Hefei, China.

The results add to a growing body of literature about a controversial link between maternal thyroid hormones in pregnancy, when the fetal brain is developing, and subsequent behavior in preschool children, Caroline T. Nguyen, MD, who was not involved with this research, commented in an email.

“Some studies show an association between thyroid levels and behavioral outcomes, others not,” added Dr. Nguyen, assistant professor of clinical medicine, Keck School of Medicine, University of Southern California, Los Angeles. And “some studies have found sex-specific associations with maternal thyroid levels and neurocognitive/behavioral outcomes, others have not.”

Women considering pregnancy should be evaluated for possible thyroid disease, she continued. Currently, no universal screening mandates exist for thyroid disease in pregnancy, but the 2017 American Thyroid Association guidelines do recommend screening women at risk for thyroid dysfunction.

“I think screening for thyroid peroxidase antibody (TPOAb) positivity is helpful in women desiring pregnancy,” Dr. Nguyen continued, “because we know that patients with TPOAb positivity are at increased risk for miscarriage and have a blunted response to the increased demands of pregnancy for thyroid hormone production.”

TPOAb positivity is also associated with the increased risk of postpartum and long-term thyroid dysfunction.

This current study, Dr. Nguyen summarized, “adds to a growing body of research of the relationship of thyroid hormone levels and neurocognitive outcomes [in offspring] and supports the monitoring of thyroid disease in pregnancy.”

“However, we do not have sufficient data to demonstrate the benefits of intervention with levothyroxine treatment,” she noted.

Nevertheless, the lack of positive data does not suggest there is no theoretical benefit of intervention, she said, as such studies are very challenging to do.

“Physicians can help reduce stress and anxiety in patients desiring pregnancy by [recommending] preconception counseling, screening patients at risk for thyroid disease, and optimizing thyroid hormone levels before and during pregnancy,” according to Dr. Nguyen.


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