In a new study, researchers found the timing of anemia—a common condition in late pregnancy—can make a big difference for the developing fetus.
They found a link between early anemia and increased risk of autism, ADHD and intellectual disability in children. But anemia discovered toward the end of pregnancy did not have the same correlation.
The research was conducted by a team from Karolinska Institutet.
An estimated 15 to 20 percent of pregnant women worldwide suffer from iron deficiency anemia, a lowered ability of the blood to carry oxygen that is often caused by a lack of iron.
The vast majority of anemia diagnoses are made toward the end of pregnancy, when the rapidly growing fetus takes up a lot of iron from the mother.
In the current study, the researchers examined what impact the timing of an anemia diagnosis had on the fetus’ neurodevelopment.
They focused on if there was an association between an earlier diagnosis in the mother and the risk of intellectual disability (ID), autism and ADHD in the child.
Overall, very few women are diagnosed with anemia early in pregnancy.
In this study of nearly 300,000 mothers and more than half a million children born in Sweden between 1987-2010, less than 1 percent of all mothers were diagnosed with anemia before the 31st week of pregnancy.
Among the 5.8 percent of mothers who were diagnosed with anemia, only 5 percent received their diagnosis early on.
The researchers found that children born to mothers with anemia diagnosed before the 31st week of pregnancy had a somewhat higher risk of developing autism and ADHD and a significantly higher risk of intellectual disability compared to healthy mothers and mothers diagnosed with anemia later in pregnancy.
Among the early anemic mothers, 4.9% of the children were diagnosed with autism compared to 3.5% of children born to healthy mothers, 9.3% were diagnosed with ADHD compared to 7.1%; and 3.1% were diagnosed with intellectual disability compared to 1.3% of children to non-anemic mothers.
The researchers concluded that the risk of autism in children born to mothers with early anemia was 44% higher compared to children with non-anemic mothers, the risk of ADHD was 37% higher and the risk of intellectual disability was 120% higher.
The findings underscore the importance of early screening for iron status and nutritional counseling.
Different parts of the brain and nervous system develop at different times during pregnancy, so an earlier exposure to anemia might affect the brain differently compared to a later exposure.
One author of the study is Renee Gardner, project coordinator at the Department of Public Health Sciences at Karolinska Institutet.
The study is published in JAMA Psychiatry.
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