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A new study by UC-Davis researchers found a five-fold increase in autism spectrum disorder in children born to mothers with low iron intake and some metabolic conditions.

“Iron deficiency and its resultant anemia is the most common nutrient deficiency … affecting 40 to 50% of women and their infants,” said Rebecca Schmidt, assistant professor at the UC-Davis Department of Public Health Sciences and a MIND Institute researcher, in a written statement.

“Iron is crucial to early brain development, contributing to neurotransmitter production, myelination and immune function,” Schmidt said. “All three of these pathways have been associated with autism.”

Research has been conducted previously on the link between autism and mother’s intake of folic acid, but this research is the first to look at iron intake as a possible contributor, Schmidt said. UC-Davis’ MIND Institute — Medical Investigation of Neurodevelopmental Disorders — is a collaborative international research center examining causes and treatment of neurodevelopmental disorders.

The study is expected to be published online this week by the American Journal of Epidemiology.

The mothers who were at five times’ greater risk for having a child with autism not only had low iron intake but also were over age 35 and suffered from metabolic conditions — including obesity, hypertension or diabetes. However, mothers under age 35 without those metabolic conditions still had higher rates of autism with lower iron intake, Schmidt said.

“The risk associated with low maternal iron intake was much greater when the mother was also older and had metabolic conditions during her pregnancy,” she said.

The risk also was heightened for low-iron mothers after birth, Schmidt said.

“The association between lower maternal iron intake and increased [autism spectrum disorder] risk was strongest during breastfeeding,” Schmidt said, “after adjustment for folic acid intake.”

Schmidt pointed out that the UC-Davis study still needs replication in other studies. Schmidt and other researchers in this study also conducted a small study of the relationship between autism and folic acid intake, which was replicated in larger studies.

“We want to be cautious and wait until this study has been replicated,” she said. “In the meantime the takeaway message for women is … take vitamins throughout pregnancy, and take the recommended daily dosage,” Schmidt said, adding that women should report any side effects to their physician.