Newswise — When pregnant women in sub-Saharan Africa sleep under insecticide-treated nets, they are more likely to deliver healthy babies than unprotected women, says a new review of studies.
Mosquitoes that carry malaria parasites are most active at night. The pest-killing nets result in fewer malaria infections, miscarriages and stillbirths among mothers-to-be and fewer cases of low birth weight among their newborns.
Treated nets "should be included in strategies to try to reduce the adverse effects of malaria in pregnant women in endemic areas," say review authors led by Dr. Carrol Gamble of the University of Liverpool in England.
Each year, in malaria-prone regions of Africa, an estimated 10,000 pregnant women and 200,000 infants die as a result of malaria infection, making it the primary cause of mortality in children under five, according to the World Health Organization.
Adults generally have some acquired immunity, but when a woman becomes pregnant the parasites tend to congregate in the placenta. There they may cause severe anemia in the mother, which increases the risk of fatal hemorrhage during delivery. The parasites also hijack nutrients intended for the developing fetus, threatening its development and survival.
The review appears in the most recent issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
To compare pregnancy outcomes in women who used insecticide-treated nets and those who did not, the reviewers identified four randomized controlled trials conducted in sub-Saharan Africa. Review co-author Feiko ter Kuile is an author of two of these trials.
The studies comprised more than 6,400 pregnant women and showed that bed nets reduced the risk of parasite infection in the placenta by 21 percent. In women carrying their first to fourth babies, these nets reduced the occurrence of miscarriages or stillbirths by 33 percent and underweight newborns by 23 percent. The effects on severe anemia in the mothers were inconclusive.
The review included another trial of 341 women in Thailand, which compared insecticide-treated nets with untreated nets. This trial showed that women using treated nets were less likely to have anemia or miscarriages, but the insecticide had no impact on other outcomes.
Malaria in Asia and Latin America is generally caused by less deadly parasite species than the one that predominates in Africa. Moreover, people often do not have acquired immunity in these regions, so illness and mortality patterns are quite different. Further research is required before use of nets can be recommended in these areas, say the authors.
The World Health Organization sees insecticide-treated nets as a critical adjunct to medications in preventing malaria-related illness and death in Africa, according to Dr. Juliana Yartey of the group's Department of Making Pregnancy Safer.
More than 70 percent of African women receive prenatal care at least once during pregnancy, said Yartey, and WHO recommends that all receive an insecticide-treated net at their first clinic visit. In rural and hard-to-reach areas, these nets are often distributed through campaigns and outreach programs. Yartey said that sleeping under an insecticide-treated net offers direct protection to a woman, along with her husband and any children who share her bed. These nets also offer indirect protection to others in the household and community by reducing the overall population of disease-carrying mosquitoes.
"Reducing malaria in pregnant women is not an individual benefit, it is a societal benefit," Yartey said. "We need to provide free insecticide-treated nets to pregnant women to benefit the mother, her child, the rest of the family, and the community."
Gamble C, Ekwaru JP, ter Kuile FO. Insecticide-treated nets for preventing malaria in pregnancy. The Cochrane Database of Systematic Reviews 2006, Issue 2.
The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. Visit http://www.cochrane.org for more information.
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