Anemia during pregnancy may be linked to differences in how a baby’s brain develops during the first two years of life, according to new research from South Africa.
In an observational study published in Brain Communications, researchers followed 394 mother-child pairs and scanned a subgroup of babies between about 3 months and 2 years old. Babies born to mothers who had anemia during pregnancy had smaller overall brain volumes and smaller volumes in a few specific areas of the brain. Those differences became easier to see around age 1 and, in some areas, were larger by age 2.
Because this was an observational study, it cannot prove that anemia caused the differences. It also did not show whether the children had differences in intelligence, behavior, movement, learning or school performance.
Most of the mothers who had anemia had mild cases.
In the larger group scanned with a portable MRI machine, babies born to mothers with anemia had about 4% smaller total brain volume across the first two years of life. Researchers also saw differences in a few areas involved in movement, learning and communication within the brain.
One of the clearest differences was in the corpus callosum, the band of tissue that helps the two halves of the brain communicate. Its volume was about 4% smaller at 12 months and about 6% smaller at 24 months among children whose mothers had anemia during pregnancy.
“What is striking about these findings is how early we are able to detect them,” said first author Jessica Ringshaw of King’s College London and the University of Cape Town.
The differences were not obvious in the first few months of life. They became more noticeable as the babies got older.
The study took place in Gugulethu, an urban community in Cape Town where anemia, food insecurity and infectious disease are common. About 30% of the mothers in the imaging groups had anemia during pregnancy, and most cases were mild.
That setting is important because anemia can have several causes.
Iron deficiency is the most common cause, but anemia can also be related to infection, inflammation and other health conditions. In this group, about half of the mothers with anemia were thought to have iron deficiency, while mothers living with HIV were also more likely to have anemia.
The researchers also looked specifically at iron deficiency during pregnancy, but they did not find a clear link between iron deficiency alone and babies’ brain volumes. That part of the analysis included a much smaller group, so the authors say the result should be interpreted cautiously.
That means the study should not be read as a simple story about iron.
It does not show that every case of anemia in pregnancy comes from low iron, and it does not show that taking more iron would necessarily prevent the brain differences seen here.
Instead, the findings suggest that anemia during pregnancy may be an important sign that deserves attention, while the underlying cause may differ from person to person.
The researchers also checked whether babies who later developed anemia themselves had smaller brain volumes. They did not find a clear link. The stronger association was with whether the mother had anemia during pregnancy.
That builds on earlier South African research that found similar brain differences in toddlers and school-age children whose mothers had anemia during pregnancy.
The new study shows those differences can be detected much earlier, beginning around the first year of life.
“Seeing such prominent volumetric differences in infants exposed to anaemia in the womb reinforces the importance of optimising interventions for women both before and during pregnancy,” Ringshaw said.
The study also tested a newer kind of MRI scanner that is cheaper, quieter and easier to use outside large hospitals.
Researchers found that the portable scanner could detect similar patterns to a standard hospital MRI. That could make this kind of research easier in places where anemia is common but access to traditional MRI is limited.
There are still important limitations.
The study was conducted in one South African community, so the findings may not apply in the same way everywhere. Mothers with anemia also differed in some ways from those without it, including household income and HIV status. The researchers adjusted for those factors in additional analyses, but other unmeasured differences could still play a role.
And smaller brain volume does not automatically mean a child will have developmental problems.
This study looked at brain structure, not how the children thought, learned, behaved or moved. More research is needed to understand what the differences mean over time.
The research was supported by the Wellcome Leap 1kD program, the Wellcome Trust, the Gates Foundation, the Developing Excellence in Leadership, Training, and Science in Africa program, the UK Foreign, Commonwealth, and Development Office, the European Union and the National Institute for Health and Care Research Maudsley Biomedical Research Centre.