Literatures published up to April 2012 were retrieved from PubMed, Embase and Cochrane library, Chinese National Knowledge Infrastructure (CNKI), Chinese Scientific and Technological Periodical Database (VIP), Wangfang, and Traditional Chinese Medicine online. Two researchers collected data independently. The assessment of methodological quality was based on Cochrane handbook and the materials were analyzed with software RevMan 5.1.2. The outcome measure index was relative risk or difference of mean value (95% confidence interval). The following outcomes were evaluated (1) general clinical improvement rate; (2) maximum vertical pocket depth; (3) amniotic fluid index (AFI) value; (4) rate of fetal ductus arteriosus constriction; (5) incidence of adverse events.

Based on the search strategy, 5 trails involving 1017 patients were finally included. Compared with therapy C, therapy A decreased the rate of fetal ductus arteriosus constriction (P<0.01). Therapy B was more effective than therapy C in general clinical improvement and decrease of AFI for polyhydramnios (P<0.01). No serious adverse events were reported in therapy A and therapy B.

Compared with therapy C, therapy A and therapy B may appear to be more effective for polyhydramnios. However, the exact effect needs to be confirmed with well-designed large-scale clinical trials.

Key words: Chinese herbal medicine, polyhydramnios, meta-analysis, systematic review