Early anemia in pregnant women linked with significantly higher risk of intellectual disability in children
The researchers also found that children born to mothers with anemia diagnosed within the first 30 weeks had a modest risk of developing autism, ADHD; Anemia discovered toward the end of pregnancy did not have the same associations
The timing of anemia, which is a common condition in late pregnancy, can make a massive difference for the developing fetus. Researchers from Karolinska Institutet have found that children born to mothers with anemia diagnosed earlier in pregnancy - within the first 30 weeks - had a significantly higher risk of developing intellectual disability and a somewhat higher risk of developing autism spectrum disorder (ASD), and attention-deficit/hyperactivity disorder (ADHD), as compared to healthy mothers and mothers diagnosed with anemia later in pregnancy.
After considering other factors such as income level and maternal age, the researchers concluded that the risk of intellectual disability in children born to mothers with early anemia was 120% higher, the risk of autism was 44% higher, and the risk of ADHD was 37% higher, as compared to children with non-anemic mothers. However, anemia diagnosed after the 30th week of pregnancy was not associated with a higher risk for any of these conditions, says the study published in JAMA Psychiatry. According to the researchers, the findings underscore the importance of early screening for iron status and nutritional counseling.
"A diagnosis of anemia earlier in pregnancy might represent a more severe and long-lasting nutrition deficiency for the fetus. 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," says lead researcher Renee Gardner, who is the project coordinator at the Department of Public Health Sciences at Karolinska Institutet.
The researchers say the findings could be the result of iron deficiency in the developing brain and may thus support a "protective role for iron supplementation in maternity care." Adult women typically need 15 mg of iron per day, though requirements might increase later in pregnancy. Since excessive iron intake can be toxic, the researchers recommend that pregnant women should discuss their iron intake with their doctor or midwife.
Among the early anemic mothers, 4.9% of the children were diagnosed with autism compared to 3.5% of children born to healthy mothers. Similarly, among early anemic mothers, 9.3% of their children were diagnosed with ADHD compared to 7.1%. Further, 3.1% were diagnosed with intellectual disability compared to 1.3% of children born to non-anemic mothers.
The study involved 532,232 individuals between 6 and 29 years of age at the end of follow-up and their 299,768 mothers. The team used data from the Stockholm Youth Cohort, a register-based cohort of individuals born from January 1, 1984, to December 31, 2011, residing in Stockholm County at any point from January 1, 2001, to December 31, 2011. During 31,018 pregnancies (5.8%), mothers were diagnosed with anemia. Of these diagnoses, 1,534 (5.0%) occurred before 30 weeks of pregnancy and 28,198 (90.9%) occurred after 30 weeks of pregnancy.
An estimated 15-20% of pregnant women globally 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, among the 5.8 % pregnant women who were diagnosed with anemia, only 5% received their diagnosis early on.
"Iron deficiency and anemia are common during pregnancy, with an estimated prevalence of 30% to 50% for iron deficiency, and 15% to 20% for iron deficiency anemia. Iron demands increase in pregnancy to support the growing fetus and placenta and expand the maternal red blood cell mass. Severe maternal iron shortage can lead to fetal and neonatal iron deficiency," says the study.
The researchers also found that children born to mothers with anemia diagnosed at 30 weeks or less were more likely to be born preterm or small for gestational age, compared with children whose mothers were not diagnosed with anemia. "Children whose mothers were diagnosed with anemia at greater than 30 weeks' were more likely to be born post-term, and large for gestational age," the findings state.
Given that iron deficiency and anemia are common among women of child-bearing age, the researchers have recommended early screening for iron status. They, however, suggest that more research is needed to find out if early maternal iron supplementation could help reduce the risk of neurodevelopmental disorders in children.