Low iron in pregnancy linked to newborn heart disease in ‘gamechanger’ discovery

Women who suffer from low iron levels in pregnancy are much more likely to have a baby with heart disease, experts have found in a “gamechanger” discovery.

For the first time, researchers have linked anaemia in early pregnancy and congenital heart disease, which is when heart problems develop in the womb and are present from birth.

As a result of the findings, researchers now estimate that anaemia in pregnant women may account for around one in 20 congenital heart disease cases in the UK.

The condition is the most common kind of birth defect, diagnosed in an average of 13 babies every day in the UK, and is a major cause of death.

Nearly a quarter of pregnant women in the UK – and more than a third of pregnant women globally – are thought to have anaemia.

As part of the new work, published in BJOG: An International Journal of Obstetrics and Gynaecology, experts will now investigate whether taking iron supplements before and during pregnancy could help prevent heart defects.

The study looked at data from 16,500 mothers and found that, if the mother was anaemic in the first 100 days of pregnancy (around the first three months), the likelihood of having a child with congenital heart disease was much higher than usual.

The study said: “After adjusting for potential confounders, the odds of giving birth to a congenital heart disease-diagnosed child were 47% higher among anaemic mothers.”

It is is already known that severe anaemia in the later stages of pregnancy causes problems such as low birth weight and premature delivery, but this is the first time anaemia in the early stages has been identified as an issue.

Associate professor Duncan Sparrow, from the University of Oxford, who led the study funded by the British Heart Foundation, said: “Knowing that early maternal anaemia is so damaging could be a gamechanger worldwide.

“Because iron deficiency is the root cause of many cases of anaemia, widespread iron supplementation for women – both when trying for a baby and when pregnant – could help prevent congenital heart disease in many newborns before it has developed.”

The researchers previously found a link between anaemia during pregnancy and congenital heart disease in mice.

To investigate this link, they used anonymised data from GP records to see what was happening in mothers and babies.

More than 2,700 mothers who had a child with congenital heart disease were identified and matched with women whose children did not have the condition.

Blood test results from the first 100 days of each pregnancy were then used to determine whether the mothers had anaemia at that point.

In the group of mothers who had a child with congenital heart disease, 4.4% had anaemia.

This was compared to 2.8% of mothers having anaemia whose children did not develop congenital heart disease.

Dr Sonya Babu-Narayan, clinical director at the British Heart Foundation and consultant cardiologist, said: “If low iron turns out to be one of the culprits, then replenishing iron levels during early pregnancy when the baby’s heart is forming could have significant benefit for a baby’s lifelong heart health.

“Larger studies are needed to confirm the finding and determine which type of congenital heart disease may be linked to low iron.

“It is also important to note that the usual risk of having a child with a congenital heart disease is around 1%, so even with the increase that this study suggests, the individual risk for people with no family history of congenital heart disease is still relatively small.”