Iron deficiency anemia in early pregnancy raises risk of heart defects – study

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Iron deficiency and anemia early in pregnancy can significantly increase a child’s risk of heart defects, new research suggests.

A team of researchers from the University of Oxford have identified a brand new risk factor for congenital heart disease (CHD) using mouse models.

Affecting 12 babies born each day in the UK, coronary artery disease is the most common birth defect in humans.

Babies with coronary artery disease are born with one or more structural defects caused when the heart does not develop properly in the womb.

Anemia is a major global health problem, affecting 20-40% of women of reproductive age, a total of over 500 million people, half of which are due to iron deficiency

The condition is a major cause of infant mortality and requires continuous medical treatment throughout life.

However, it is not always clear why this happens.

Coronary artery disease can be caused by a genetic abnormality inherited from one or both parents, such as a genetic mutation.

Mutations in these genes can only explain about a third of cases, while more than 100 genes have been associated with individual cases of disease.

The cause of coronary heart disease in the other two-thirds of cases is often unknown.

In many of these unknown cases, it is most likely caused by exposure of the embryo to an abnormal environment in the womb early in pregnancy, researchers say.

However, the disease is not routinely detected until after 20 weeks of pregnancy, so it has been difficult to collect data on maternal physiology during the first trimester to establish new risk factors for birth defects.

Duncan Sparrow, Associate Professor at the University of Oxford, Principal Investigator of the British Heart Foundation (BHF) and principal investigator of the study, said: “Severe maternal iron deficiency in the second and third trimesters is well known to increase the risk of having a low birth weight baby and preterm delivery.

“However, we are specifically looking for maternal iron deficiency in the first trimester for the first time, and we show in mice that maternal iron deficiency can cause severe cardiovascular malformations in its offspring.”

The researchers say their findings are supported by a 2020 epidemiological study from China that suggests the risk of having a child with coronary artery disease may be increased threefold in women who have low iron intake early in pregnancy.

Professor Sparrow said: “Anaemia is a major global health problem, affecting 20-40% of women of reproductive age, a total of over 500 million people, and half of these are due to iron deficiency.

“Thus, if our findings are applicable to humans, it may explain why congenital heart disease is relatively common around the world.”

Research also indicates that the risk of coronary artery disease can be significantly reduced if the mother receives iron supplements, provided this occurs very early in pregnancy before the heart has formed in the embryo.

Dr Jacinta Kalisch-Smith, first author of the paper, said: ‘In humans, the heart forms between weeks three to nine.

“Our results from the animal study suggest that iron supplementation would probably need to be given before the third week to be effective.

“Better to take supplements while trying to conceive because women may not know they are pregnant at such an early stage.

“This adds further evidence in support of WHO’s global health priority of ensuring that women of childbearing age do not suffer from iron deficiency.

“In fact, the WHO recommends that supplementation should begin as early as possible and continue throughout pregnancy.”

The research team hopes that their findings can be translated into clinical practice to ultimately reduce the birth prevalence of coronary heart disease worldwide.

The research was funded by the British Heart Foundation (BHF).