Iron during pregnancy and its effects on fetal brain development
What it found
Low iron during pregnancy is linked to poorer memory, slower processing speed, and long-term mental health risks in children.
Animal studies show that a lack of iron changes how the developing brain builds connections and controls chemical signals.
What they found
Studies in people
How much iron pregnancy needs
Pregnancy requires an extra 1 gram of iron, split roughly equally between the mother and the baby. Each extra gram of hemoglobin the mother makes needs 3.46 milligrams of iron. In lower-income countries, low iron rates approach 80% during pregnancy, while well-resourced countries see about 45%.
Memory and processing in babies
Newborns with low iron stores showed weaker recognition memory and slower brain signal speeds. These issues were still seen at 3.5 to 4 years of age, even after iron levels returned to normal. Low iron intake in the second trimester was also tied to a 30% higher risk of schizophrenia in offspring.
Testing for low iron
Measuring hemoglobin alone misses early iron shortage because the body sends iron to red blood cells first. Checking ferritin alongside hemoglobin gives a clearer picture, though inflammation can make ferritin look falsely high. A newer test measuring hepcidin may help doctors decide who truly needs extra iron.
Baby iron stores after birth
A full-term baby normally holds about 75 mg of iron per kilogram of body weight, mostly in red blood cells and the liver. Human milk has very little iron, so babies rely on these stores for their first four to six months. Delaying cord clamping helps improve the baby's hemoglobin at 2 months of age.
Animal and lab studies
Brain changes in animals
In animal studies, fetal iron shortage cut brain oxygen use by 60% and led to simpler nerve cell structures. It also changed brain chemicals like dopamine and serotonin, and these changes lasted into adulthood even after iron was restored.
Other findings
Fetal brain uses most oxygen
The growing fetal brain uses 60% of all the oxygen the fetus consumes. Iron helps cells turn oxygen into energy, making it vital for the brain as it folds and matures from 24 weeks until birth.
What the authors conclude
- They argue that protecting childhood brain health must start before conception and continue through pregnancy, rather than focusing only on nutrition after birth.
- The authors call for policies that support maternal nutrition before pregnancy and ensure key nutrients like iron are provided during gestation.
- They view this life-cycle approach to nutrition as an investment in the mental health of future generations.
How it was done
Pregnancy greatly increases the body's need for iron as the mother's blood volume grows and the fetus develops. The authors wanted to explain how to spot low iron early and why it matters so much for the baby's brain.
The authors gathered and examined existing research on iron needs during pregnancy, how to measure iron levels, and what happens when mothers or babies do not get enough. They looked at studies in pregnant women, newborns, children, and animal models of fetal iron shortage.
What it can’t tell you
- Because this work gathers past research, it cannot prove on its own that low iron directly causes conditions like autism or schizophrenia.
- Many findings about brain structure and chemical signals come from animal models and may not match exactly what happens in people.
- Studies that follow children over time can show links but cannot rule out other factors that might explain the results.
Who paid
- Funding
- Funded by NICHD NIH HHS; NINDS NIH HHS (from the PubMed record).
- Conflicts
- The author has no conflicts of interest to report.
- Authors work at
- University of Minnesota Medical School, MN
The paper
- Title
- Iron deficiency in pregnancy
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Georgieff MK (2020). Iron deficiency in pregnancy. American journal of obstetrics and gynecology. doi:10.1016/j.ajog.2020.03.006Free full textPubMed 32184147DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error