A major international study led by Liverpool School of Tropical Medicine (LSTM) has confirmed that the drug used to prevent malaria in pregnancy continues to protect babies' health, despite malaria parasites developing high levels of drug resistance.
The study, published in The Lancet Infectious Diseases, analysed data from 122 studies involving nearly 150,000 pregnant women across sub-Saharan Africa on the effects of using sulfadoxine-pyrimethamine (SP) for the prevention of malaria in pregnancy.
In 2023, an estimated 12.4 million pregnant women in Africa were infected with malaria. The disease increases the risk of miscarriage, severe maternal anaemia, and babies being born too small or too early. SP has long been a key drug for protecting pregnant women from the effects of malaria infection. However, the spread of resistant malaria strains has raised concerns about its ongoing value.
Researchers found that while SP becomes less effective at preventing malaria infections as resistance increases, it still has other beneficial effects for developing pregnancies. Across all resistance levels, SP reduced the risk of low birth weight by around 25% to 45%, with no evidence that higher resistance weakened these effects. These benefits appear to work through mechanisms separate from preventing malaria and may be a result of SP being a broad-spectrum antibiotic.
Dr Anna Maria van Eijk, who led the study from LSTM's Department of Clinical Sciences, said: "Even in areas where this drug's ability to prevent malaria is compromised, it still protects babies from being born too small through beneficial effects that are not related to malaria. That's an incredibly important result for maternal and child health."
These findings provide essential guidance for healthcare providers and policymakers. Crucially, this new analysis confirms that SP should continue to be used in antenatal care programmes because of its benefits for birth outcomes. The research also found no evidence of harm from continued SP use in pregnancy.
Professor Feiko Ter Kuile, joint senior author and Professor of Tropical Medicine at LSTM, said: "These findings provide crucial guidance for malaria control programmes. Whilst we must continue our search for more effective alternatives, this research shows that current prevention strategies continue to provide important benefits for maternal and child health."
SP remains the only drug recommended by the World Health Organization (WHO) for malaria prevention during pregnancy in Africa. While the findings are reassuring, the researchers stress that there is still an urgent need to develop new drugs, vaccines, or other strategies to protect pregnant women from malaria and improve outcomes for mothers and babies. They also highlighted the urgent need to better understand the malaria-independent effects of SP.
The study was conducted by the IPTp Effectiveness Study Group, comprising researchers from across Africa, Europe, and the United States. It was funded by the WHO and the WorldWide Antimalarial Resistance Network, which is supported by the Bill & Melinda Gates Foundation.