Safety and efficacy of black cohosh (Cimicifuga racemosa) during pregnancy and lactation.

BACKGROUND: There is a lack of basic knowledge on the part of both clinicians and patients as to the indications for use and safety of herbal medicines in pregnancy and lactation. This is one article in a series that systematically reviews the evidence for commonly used herbs during pregnancy and lactation. OBJECTIVES: To systematically review the literature for evidence on the use, safety, and pharmacology of black cohosh focusing on issues pertaining to pregnancy and lactation. METHODS: We searched 7 electronic databases and compiled data according to the grade of evidence found. RESULTS: Black cohosh, alone or in combination with other medicinal herbs as "mother's cordial", has a long traditional use and is frequently used by midwives as a uterine stimulant and labour-inducing aid. Low-level evidence based on theory and expert opinion shows the following concerns with respect to black cohosh use during pregnancy: 1) labour-inducing effects, 2) hormonal effects, 3) emmenagogue properties and, 4) anovulatory effects. During lactation, there is low-level evidence from theoretical and expert opinion of black cohosh having hormonal properties. CONCLUSIONS: Black cohosh should be used with caution during pregnancy, particularly during the first trimester where its purported labour-inducing effects could be of concern, and during lactation. Black cohosh should undergo rigorous high quality human studies to determine its safety in pregnancy and lactation.