The safety of St John's wort (Hypericum perforatum) in pregnancy and lactation : a systematic review of rodent studies

Herbal products are popular among women during the perinatal period. St John's wort (SJW), Hypericum perforatum, is a common remedy for mild depression, a problem prevalent in this population. Although the safety of herbal products must be investigated, ethical issues constrain intervention studies in humans. Hence, animal studies often inform clinical decisions. The objective of this study is to systematically review rodent studies assessing the safety of SJW during the perinatal period. A literature search to November 10, 2017, identified 10 rodent studies that met a priori inclusion criteria. Study quality was evaluated according to both the Systematic Review Centre for Laboratory animal Experimentation tool for assessing bias and recommendations for appropriate reporting of herbal medicine research. Significant methodological limitations were found in each of the studies reviewed. These limitations include the lack of botanical verification and omission of extract characterization, inadequate explanation of dosage rationale, and absence of bias limiting protocols. Critical appraisal with contemporary tools indicates that each of the reviewed studies lacks appropriate rigour, rendering the results unreliable. Despite this, these papers are used in the rationale for recommending or contraindicating SJW during pregnancy and lactation.