According to the largest study on the effects of malaria and different anti-malarial drugs in early pregnancy to date, just one episode of malaria in the first trimester is linked to a three-fold greater risk of miscarriage. Researchers also discovered that women treated with anti-malarial drugs did not suffer any serious side effects or increase their likelihood of miscarriage. The study was published Online First in The Lancet Infectious Diseases.

According to estimates each year, 125 million pregnancies are at risk of malaria. During pregnancy, malaria can cause both severe anemia and parasitic infection in the fetus and increase the risk of low birth-weight, preterm birth, and maternal death.

Until now, scientists know little about the effects of malaria in early pregnancy or the benefits and harms of anti-malarial drugs during the early stages of pregnancy. The treatment of all falciparum malaria is artesunate-based combination therapy (ACT), however, it is not recommend during the first pregnancy trimester as it has been proven toxic in animal studies, potentially causing birth defects or miscarriage.

Leading author Rose McGready from Shoklo Malaria Research Unit in Thailand, explained:

“Both vivax and falciparum malaria contribute significantly to avoidable fetal and infant death. These results suggest that the adverse effects of malaria in the first trimester substantially outweigh any adverse effects of its treatment…[and] emphasizes the importance of early detection of malaria and prompt effective treatment for all pregnant women.”

McGready and his team set out to provide more evidence and reviewed records of pregnant women who attended antenatal clinics of the Shoklo Malaria Research Unit on the northwestern border of Thailand between May 1986 and October 2010. They compared outcomes of 16,668 women who no malaria during pregnancy with 945 women who had only a single episode in the first trimester, i.e. at less than 14 weeks into their pregnancy, and discovered that asymptomatic malaria, showing no noticeable symptoms, was linked to almost a three times higher risk of miscarriage compared with those who did not contract malaria, whilst the risk of miscarriage for those with symptomatic malaria tended to be at least four-times more likely. In women with vivax and falciparum malaria the risk of miscarriage was similar.

The researchers discovered that the chances of miscarriage was comparable in women who received chloroquine (26%), quinine (27%), and artesunate (31%) during the first-trimester, with no substantial difference reported between treatments in other birth outcomes, such as still birth or low birth weights. Unlike the findings from animal studies, the researchers detected no additional toxic effects in women treated with artesunate.

The authors comment: “Miscarriage in 24 first-trimester episodes of hyperparasitaemia or severe malaria was high but artesunate did not result in higher rates of miscarriage than did quinine,” and conclude saying, that: “These findings have serious implications for malaria treatment and prevention policies, which currently ignore the first trimester…A randomized trial of first-trimester artemisinin-based treatment is now needed to make firm recommendations on the safety of first-trimester malaria treatments with this class of anti-malarial drug.”

Meghna Desai and Stephanie Dellicour from the Kenya Medical Research Institute/Centers for Disease Control and Prevention, Kisumu, Kenya write in an associated comment:

“This study provides a level of reassurance regarding the potential risk associated with artemisinin exposure in early pregnancy, compared with the established risk of malaria. This study, combined with data from ongoing studies done in sub-Saharan Africa, will for the first time allow an informed risk/benefit assessment of disease versus treatment with artemisinin combination treatments in pregnancy.”

Written by Petra Rattue