Pregnant women with weak thyroid are four times more likely to have autistic children, a latest study reveals.
Researchers at Houston Methodist Neurological Institute and Erasmus Medical Centre in the Annals of Neurology, examined over 4,000 Dutch mothers and their children. They observed that a lack of maternal thyroid hormone, believed to play a vital role in embryo development, might lead to autism in children.
"It is increasingly apparent to us that autism is caused by environmental factors in most cases, not by genetics," said lead author Gustavo Roman, M.D., a neurologist and neuroepidemiologist at Nantz National Alzheimer Center. "That gives me hope that prevention is possible."
Another key factor the researchers found was that children of mothers with severely deficient T4 (thyroxine) showed distinct symptoms of autism. Children of mothers with mild T4 deficiency showed insignificant symptoms.
Severe T4 deficiency means five percent or less of normal T4, but producing a normal amount of thyroid stimulating hormone, TSH.
For the study, the team collected the blood samples of women into their 13th week of pregnancies. These women were involved in a study between 2002 and 2006. They studied the samples to understand the levels of T4 and two proteins that could indicate the cause of thyroid deficiency.
After six years the mothers were asked about the behavioral and emotional personalities of their children with the help of a standardized psychology checklist. The researchers found 80 "probable autistic children" out of the studied 4,039 children.
The results further revealed that 159 mothers were diagnosed with severely deficient T4. According to the experts, the main cause of thyroid hormone deficiency is a lack of dietary iodine. "If you are planning to become pregnant, have your doctor measure urine iodine and thyroid function beforehand. If you have just become pregnant, have your doctor measure urine iodine, thyroid function, and begin using prenatal vitamins, making sure iodine is present," Roman advised.
Lack of proper dietary iodine also leads to pregnancy complications, deafness and developmental delay in the infants. Negative effects such as loss of control of fat and sugar metabolism and heat generation are seen in mothers with weak thyroid.
