Anemia during early pregnancy tied to cognitive decline, ADHD and autism in children: JAMA
Anemia is one of the most common and leading risk factors for maternal and foetal complications. Majority of diagnosis related to anemia is done in the last trimester of pregnancy as the fetus takes up most of the iron from the mother's body. A recent study published in the Journal of American Medical Association (JAMA) has revealed that children born to mothers with anemia diagnosed before the 31st week of pregnancy have a higher risk of developing autism and Attention deficit hyperactivity disorder (ADHD) and a significantly higher risk of intellectual disability compared to healthy mothers and mothers diagnosed with anemia later in pregnancy.
In the current study, the researchers examined what impact the timing of an anemia diagnosis had on the fetus' neurodevelopment, in particular, if there was an association between an earlier diagnosis in the mother and the risk of intellectual disability (ID), autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (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. Among the early anemic mothers, 4.9 percent of the children were diagnosed with autism compared to 3.5 percent of children born to healthy mothers, 9.3 percent were diagnosed with ADHD compared to 7.1 percent; and 3.1 percent were diagnosed with intellectual disability compared to 1.3 percent of children to non-anemic mothers.
After considering other factors such as income level and maternal age, the researchers concluded that the risk of autism in children born to mothers with early anemia was 44 percent higher compared to children with non-anemic mothers, the risk of ADHD was 37 percent higher and the risk of intellectual disability was 120 percent higher. Even when compared to their siblings, children exposed to early maternal anemia were at higher risk of autism and intellectual disability. Importantly, anemia diagnosed after the 30th week of pregnancy was not associated with a higher risk for any of these conditions.
Key findings of the study are as follows
- The prevalence of ASD, ADHD, and ID was higher among children born to mothers diagnosed with anemia within the first 30 weeks of pregnancy (4.9% ASD, 9.3% ADHD, and 3.1% ID) compared with mothers with anemia diagnosed later in pregnancy (3.8% ASD, 7.2% ADHD, and 1.1% ID) or mothers not diagnosed with anemia (3.5% ASD, 7.1% ADHD, and 1.3% ID).
- Anemia diagnosed during the first 30 weeks of pregnancy but not later was associated with increased risk of diagnosis of ASD, and ID in offspring in models that included socioeconomic, maternal, and pregnancy-related factors.
- Early anemia diagnosis was similarly associated with risk of ASD and ID in a matched sibling comparison.
- Considering mutually exclusive diagnostic groups, we observed the strongest association between anemia and ID without co-occurring ASD.
- Associations of these disorders with anemia diagnosed later in pregnancy were greatly diminished.
"A diagnosis of anemia earlier in pregnancy might represent a more severe and long-lasting nutrition deficiency for the fetus," says Renee Gardner, project coordinator at the Department of Public Health Sciences at Karolinska Institutet and the study's lead researcher. "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."
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