Context: Empiric use of medical and nutritional supplements to improve semen parameters and pregnancy rates in couples with idiopathic infertility has reached global proportions, although the evidence base for their use in this setting is controversial.
Objective: We systematically reviewed evidence comparing the benefits of nutritional and medical therapy on pregnancy rates and semen parameters in men with idiopathic infertility.
Evidence acquisition: A literature search was performed using MEDLINE, Embase, LILACS, and the Cochrane Library (searched from January 1, 1990 to September 19, 2017). using the methods detailed in the Cochrane Handbook. Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess the certainty of evidence.
Evidence synthesis: The literature search identified 5663 citations, and after screening of abstracts and full texts, 61 studies (59 randomised controlled trials and two nonrandomised comparative studies) were included. Pooled results demonstrated that pentoxyfylline, coenzyme Q10, L-carnitine, follicle-stimulating hormone, tamoxifen, and kallikrein all resulted in improvements in semen parameters. Individual studies identified several other medical and nutritional therapies that improved semen parameters, but data were limited to individual studies with inherent methodological flaws. There were limited data available on live birth and pregnancy rates for all interventions. The GRADE certainty of evidence for all outcomes was very low mainly owing to methodological flaws and inconsistencies in study design. Some outcomes were also downgraded owing to imprecision of results.
Conclusions: There is some evidence that empiric medical and nutritional supplements may improve semen parameters. There is very limited evidence that empiric therapy leads to better live birth rates, spontaneous pregnancy, or pregnancy following assisted-reproductive techniques. However, the findings should be interpreted with caution as there were some methodological flaws, as a number of studies were judged to be either at high or unclear risk of bias for many domains.
Patient summary: This review identified several medical and nutritional treatments, such as pentoxyfylline, coenzyme Q10, L-carnitine, follicle-stimulating hormone, tamoxifen, and kallikrein, that appear to improve semen parameters. However, there are limited data suggesting improvements in pregnancy and live birth rates. The lack of evidence can be attributed to methodological flaws in studies and the low number of pregnancies reported.
Keywords: Infertility; Medical therapy; Meta-analysis; Nutritional therapy; Pregnancy; Systematic review.
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