Intestinal worms (helminths) contribute to iron deficiency anaemia as they feed on blood and cause further bleeding by releasing anticoagulant compounds. They also affect the supply of nutrients and cause anorexia, vomiting and diarrhoea. Pregnancy complicated by maternal hookworm infection poses a serious threat to the health of mothers and their babies, especially in developing countries. Women who are anaemic during pregnancy are more likely to have ill health, give birth prematurely, and have low birthweight babies with low iron reserves. Antihelminthic drugs are highly effective and have minimal side-effects but information on their use during pregnancy is limited. The major concern is that the drugs may cause malformation of the fetus (teratogenic effects).
The review authors found only three randomised controlled trials evaluating the impact of giving a single antihelminth treatment in the second trimester of pregnancy. The studies were conducted in Sierra Leone, Peru and Entebbe Uganda. A total of 1329 women were randomly assigned to receive a single dose of albendazole or mebendazole, or a placebo. In one study, and a subset of another, the women were also given a daily iron or iron-folate supplement. Analysis of the impact of antihelminth intervention on maternal anaemia including all results showed that the intervention was not associated with any clear impact on maternal anaemia or on low birthweight, perinatal deaths or preterm births. Analysis of studies in which iron or iron-folate was also given to pregnant women along with antihelminths also failed to show any impact on maternal anaemia. The impact on infant survival at six months of age could not be evaluated because data were not available. Evidence provided so far from randomised controlled trials is, therefore, insufficient to recommend use of antihelminthics for pregnant women after the first trimester of pregnancy.