Soil-transmitted helminths (STHs), primarily Ascaris, Trichuris and hookworm, inflict a substantial morbidity burden on poor populations living in tropical and subtropical regions. Chronic STH infections can cause intestinal blood loss and nutrient loss and/or malabsorption, which can result in or exacerbate iron deficiency, anaemia and other nutritional deficiencies. More than 1 billion people are infected with at least one STH, and at least 44 million pregnant women are infected with hookworm alone. Pregnant women are especially vulnerable to the harmful consequences of these parasitic infections due to increased nutritional demands during pregnancy. We aimed to determine the effect of antihelminthics in pregnancy on maternal, newborn and child health (MNCH) outcomes. A systematic review was conducted using online databases, and relevant articles were hand searched. We included four observational studies in the general review and four randomised controlled trials (RCTs) in the meta-analysis (total n = 3777 for the meta-analysis). Antihelminthics in pregnancy had no overall benefit on maternal anaemia [risk ratio (RR) = 0.93 [95% confidence interval (CI) 0.79, 1.10]], low birthweight (RR = 0.96 [95% CI 0.72, 1.29]) or perinatal mortality (RR = 0.98 [95% CI 0.58, 1.68]). The risk of very low birthweight was lower in the antihelminthics group (RR = 0.21 [95% CI 0.05, 0.83]); however, this estimate included data from only two trials (total n = 1936). In all four trials, antihelminthics in pregnancy significantly decreased the prevalence of STH infection. Three observational studies showed that antihelminthics in pregnancy improved maternal iron status, two studies reported beneficial effects on birthweight, and two studies found a beneficial effect on infant survival. Although few RCTs to date have failed to collectively demonstrate a clear beneficial impact of antihelminthics in pregnancy on maternal, newborn and child health outcomes, findings from observational studies suggest a potential benefit on maternal anaemia, birthweight and infant mortality. This meta-analysis was limited by a dearth of evidence from RCTs, and further trials examining the effect of antihelminthics starting in the second trimester of pregnancy in poor, STH-endemic regions with high rates of anaemia are needed.