Biophysical effects, safety and efficacy of raspberry leaf use in pregnancy: a systematic integrative review

BACKGROUND: Childbearing women have been using various herbs to assist with pregnancy, labour and birth for centuries. One of the most common is raspberry leaf. The evidence base for the use of raspberry leaf is however under-developed. It is incumbent on midwives and other maternity care providers to provide women with evidence-based information so they can make informed choices. The aim of this study was to review the research literature to identify the evidence base on the biophysical effects, safety and efficacy of raspberry leaf in pregnancy. METHODS: A systematic, integrative review was undertaken. Six databases were searched to identify empirical research papers published in peer reviewed journals including in vitro, in vivo, human and animal studies. The search included the databases CINAHL, MEDLINE, Cochrane Library, Scopus and Web of Science Core Collection and AMED. Identified studies were appraised independently by two reviewers using the MMAT appraisal instrument. An integrative approach was taken to analysis. RESULTS: Thirteen studies were included. Five were laboratory studies using animal and human tissue, two were experiments using animals, and six were human studies. Included studies were published between 1941 and 2016. Raspberry leaf has been shown to have biophysical effects on animal and human smooth muscle including the uterus. Toxity was demonstrated when high doses were administered intravenously or intaperitoneally in animal studies. Human studies have not shown any harm or benefit though one study demonstrated a clinically meaningful (though non-statistically significant) reduction in length of second stage and augmentation of labour in women taking raspberry leaf. CONCLUSIONS: Many women use raspberry leaf in pregnancy to facilitate labour and birth. The evidence base supporting the use of raspeberry leaf in pregnancy is weak and further research is needed to address the question of raspberry leaf’s effectiveness.