Anaemia in pregnancy is linked to a higher risk of negative outcomes such as preterm delivery, low birth weight, and postpartum depression.

To prevent this, the World Health Organization (WHO) recommends a daily dose of 30-60mg of iron taken orally. But a new randomised controlled trial has found that an iron infusion in the third trimester can safely and more effectively boost iron levels in people with moderate or severe anaemia.

The findings, which have been published in a Nature Medicine paper, could help improve maternal care and birth outcomes globally.

“While anaemia is one of the most avoidable causes of illness and death in resource-poor nations, any woman across the world can become anaemic during pregnancy, highlighting how this remains a global priority,” says Sant-Rayn Pasricha, corresponding author of the paper and head of the Anaemia Research Laboratory at WEHI in Australia.

Anaemia is estimated to affect about 37% of pregnant people globally and is mainly caused by iron deficiency. But the highest prevalences occur regions, like sub-Saharan Africa and South-East Asia, where a less access to healthcare, HIV, and parasitic infections such as malaria are also major contributing factors.

The trial was undertaken in rural Malawi in sub-Saharan Africa. It enrolled 590 pregnant women with moderate or severe anaemia at 27–35 weeks of gestation. Each participant received either a single iron infusion at enrolment or twice daily iron tablets for 90 days and was followed for up to 4 weeks postpartum.

“We found that a single iron infusion in the third trimester can achieve what oral iron tablets taken every day during a pregnancy cannot,” says Pasricha.

The prevalence of anaemia at 36 weeks gestation or at delivery (whichever came first) was lower in the group that received an iron infusion (46.7%) compared to those who received the current standard of care (62.7%).

In sub-Saharan Africa, only 29% of pregnant women consume an adequate treatment course of oral iron during pregnancy. By the third trimester, the time left before the onset of labour may be too short for oral iron to restore iron levels.

The findings come after a previous clinical trial by the same research group found that an iron infusion in the second trimester failed to be more effective than 90 days of iron tablets at lowering anaemia in Malawian women.

“This is the first concrete evidence that proves infusions in late pregnancy are the superior treatment for combatting anaemia in expectant mothers, boosting iron levels at a critical time that can ensure both mother and baby are better protected during birth,” says Pasricha.

The iron transfusion also reduced the prevalence of anaemia at 4 weeks post-partum.

“This sustained impact on anaemia is an unprecedented finding that really crystallises the case for using infusions in late pregnancy to rapidly boost red blood cell production and iron levels,” says Pasricha.

The treatment was safe, with no infusion-associated adverse events and no statistically significant difference in infant birthweight or infant haemoglobin concentrations between treatment groups.

“We hope our findings will soon be translated in health settings across the world to form a uniform set of guidelines that can ensure more women get the right iron treatment when they need it most,” says Pasricha.

“If intravenous iron can be safely delivered in basic health centres in remote Malawi as our trial has shown, there’s really no health setting where IV iron couldn’t be effectively and safely given.”