Systematic review of exposure to albendazole or mebendazole during pregnancy and effects on maternal and child outcomes,with particular reference to exposure in the first trimester

Soil-transmitted helminth infections cause an important burden of morbidity worldwide, primarily from blood loss and malabsorption of nutrients. Where STH endemicity ≥20%, the World Health Organization (WHO) recommends preventive chemotherapy with single dose anthelminthic drugs: albendazole or mebendazole. Although WHO recommends that women of reproductive age, including pregnant women after the first trimester, be included in large-scale deworming programs, there are concerns related to the use of anthelminthic drugs during pregnancy, especially inadvertent use in the first few weeks when the pregnancy may not yet be confirmed. We therefore conducted a systematic review using the MEDLINE database with the aim of appraising all peer-reviewed evidence, published up to July 1, 2018, on the association between exposure to albendazole or mebendazole and outcomes in pregnant women, including those in the first trimester of pregnancy, and their children. From a yield of 205 papers based on titles alone, 58 papers, reporting results from 46 originator studies conducted in pregnant populations, constituted the initial evidence base. Among the nine originator observational studies which had included women in the first trimester of pregnancy within their study population, five compared birth outcomes between women exposed in the first trimester with women who were not exposed, and none reported higher rates of adverse birth outcomes in the exposed group. Due to heterogeneity in terms of study design, sample size, deworming drug, dosage and outcomes measured, data from these studies could not be pooled. Based on this cumulative evidence, it is unlikely that inadvertent exposure to albendazole or mebendazole in the first trimester carries an additional risk of adverse birth outcomes. To optimize relevance for policy making, future research in pregnant populations should aim to provide data disaggregated by trimester and to report on maternal and child adverse events, whenever possible.