A systematic review of experimental and clinical studies of sildenafil citrate for intrauterine growth restriction and pre-term labour. 
Sildenafil could be an alternative in the treatment of intrauterine growth retardation (IUGR) and premature delivery.  In order to systematically review the reproductive-related effects of sildenafil, a search was made on PubMed and the Science Citation Index for studies evaluating the effects of sildenafil on uterine vessels or myometrium either in vitro or in experimental animal models as well as for any clinical trial or case reporting the outcome of pregnant women treated with sildenafil.  The information was obtained from: three in vitro studies, five studies performed in experimental animal models, four studies on women with fertility and sterility disorders receiving 100 mg/day of sildenafil intravaginally, and two case reports of pregnant women who received sildenafil for the treatment of pulmonary hypertension.  Incubation with sildenafil of different in vitro preparations resulted in vasodilator and uterine relaxant effects.  No evidence of teratogenicity was observed in the studies performed in mice, rats and dogs.  Sildenafil increased fetal weight in rats.  In women, contradictory results on uterine blood flow and endometrial development were reported after the intravaginal administration of sildenafil.  No adverse fetal outcomes were reported in the two pregnant women with pulmonary hypertension receiving sildenafil late in their pregnancy.  In conclusion, there is still limited information about the efficacy of sildenafil for the treatment of IUGR and premature delivery.  However, studies in experimental animal models and two human case reports have reported no deleterious effects on the mother or offspring.