BACKGROUND: Recurrent miscarriage affects 1% to 3% of women of reproductive age and mostly occurs before the 10th week of gestation (and around the same gestational week in subsequent miscarriages). Although most pregnant women may not recognise a miscarriage until uterine bleeding and cramping occur, a repeat miscarriage after one or more pregnancy loss and the chance of having a successful pregnancy varies. To date, there is no universally accepted treatment for unexplained recurrent miscarriage. Chinese herbal medicines have been widely used in Asian societies for millennia and have become a popular alternative to Western medicines in recent years. Many clinical studies have reported that Chinese herbal medicines can improve pregnancy outcomes for pregnant women who had previously suffered recurrent miscarriage. This systematic review evaluated the efficacy of Chinese herbal medicines for recurrent miscarriage. OBJECTIVES: To assess the effectiveness and safety of Chinese herbal medicines for the treatment of unexplained recurrent miscarriage. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (01 June 2015), Embase (1980 to 01 June 2015); Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 01 June 2015); Chinese Biomedical Database (CBM) (1978 to 01 June 2015); China Journal Net (CJN) (1915 to 01 June 2015); China Journals Full-text Database (1915 to 01 June 2015); and WanFang Database (Chinese Ministry of Science & Technology) (1980 to 01 June 2015). We also searched reference lists of relevant trials and reviews. We identified and contacted organisations, individual experts working in the field, and medicinal herb manufacturers. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials, including cluster-randomised trials, with or without full text, comparing Chinese herbal medicines (alone or combined with other intervention or other pharmaceuticals) with placebo, no treatment, other intervention (including bed rest and psychological support), or other pharmaceuticals as treatments for unexplained recurrent miscarriage. Cross-over studies were not eligible for inclusion in this review. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed all the studies for inclusion in the review, assessed risk of bias and extracted the data. Data were checked for accuracy. MAIN RESULTS: We included nine randomised clinical trials (involving 861 women). The trials compared Chinese herbal medicines (various formulations) either alone (one trial), or in combination with other pharmaceuticals (seven trials) versus other pharmaceuticals alone. One study compared Chinese herbal medicines and other pharmaceuticals versus psychotherapy. We did not identify any trials comparing Chinese herbal medicines with placebo or no treatment, including bed rest.Various Chinese herbal medicines were used in the different trials (and some of the classical the formulations were modified in the trials). The Western pharmaceutical medicines included tocolytic drugs such as salbutamol and magnesium sulphate; hormonal supplementation with human chorionic gonadotrophin (HCG), progesterone or dydrogesterone; and supportive supplements such as vitamin E, vitamin K and folic acid.Overall, the methodological quality of the included studies was poor with unclear risk of bias for nearly all the 'Risk of bias' domains assessed.Chinese herbal medicines alone versus other pharmaceuticals alone - the live birth rate was no different between the two groups (risk ratio (RR) 1.05; 95% confidence interval (CI) 0.67 to 1.65; one trial, 80 women). No data were available for the outcome of pregnancy rate (continuation of pregnancy after 20 weeks of gestation).In contrast, the continuing pregnancy rate (RR 1.27 95% CI 1.10 to 1.48, two trials, 189 women) and live birth rate (average RR 1.55; 95% CI 1.14 to 2.10; six trials, 601 women, Tau² = 0.10; I² = 73%) were higher among the group of women who received a combination of Chinese herbal medicines and other pharmaceuticals when compared with women who received other pharmaceuticals alone.For Chinese herbal medicines and psychotherapy versus psychotherapy alone (one study) - there was a higher live birth rate (RR 1.32; 95% CI 1.07 to 1.64; one trial, 90 women) in the group of women who received a combination of Chinese herbal medicines and psychotherapy compared to those women who received psychotherapy alone. No data were available on the continuing pregnancy rate for this comparison.Other primary outcomes (maternal adverse effect and toxicity rate and the perinatal adverse effect and toxicity rate) were not reported in most of the included studies. Two trials (341 women) reported that no maternal adverse effects were found (one trial compared (combined) medicines with other pharmaceuticals, and one trial compared combined Chinese herbal medicine alone versus other pharmaceuticals). One trial (Chinese herbal medicine alone versus other pharmaceuticals alone) reported that there were no abnormal fetuses (ultrasound) or after delivery.There were no data reported for any of this review's secondary outcomes. AUTHORS' CONCLUSIONS: We found limited evidence (from nine studies with small sample sizes and unclear risk of bias) to assess the effectiveness of Chinese herbal medicines for treating unexplained recurrent miscarriage; no data were available to assess the safety of the intervention for the mother or her baby. There were no data relating to any of this review's secondary outcomes. From the limited data we found, a combination of Chinese herbal medicines and other pharmaceuticals (mainly Western medicines) may be more effective than Western medicines alone in terms of the rate of continuing pregnancy and the rate of live births. However, the methodological quality of the included studies was generally poor.A comparison of Chinese herbal medicines alone versus placebo or no treatment (including bed rest) was not possible as no relevant trials were identified.More high-quality studies are needed to further evaluate the effectiveness and safety of Chinese herbal medicines for unexplained recurrent miscarriage. In addition to assessing the effect of Chinese herbal medicines on pregnancy rate and the rate of live births, future studies should also consider safety issues (adverse effects and toxicity for the mother and her baby) as well as the secondary outcomes listed in this review. This review would provide more valuable information if the included studies could overcome the problems in their designs, such as lacking of qualified placebo-controlled trials, applying adequate randomisation methods and avoiding potential bias.