Two micronutrients fundamental to the process of spermatogenesis, folic acid (folate) and zinc, are of particular interest for fertility as they are of low cost and wide availability. Though the evidence has been inconsistent, small randomized trials and observational studies show that folate and zinc have biologically plausible effects on spermatogenesis and improved semen parameters. These results support the potential benefits of folate on spermatogenesis and suggest that dietary supplementation with folate and zinc may help maintain and improve semen quality, and perhaps, fertility rates.
The Epidemiology Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development intends to conduct a multi-site double-blind, randomized controlled clinical trial to evaluate the effect of folic acid and zinc dietary supplementation on semen quality and conception rates among male partners of couples seeking assisted reproduction. Randomization will be stratified (with random sequences of block sizes) by site and assisted reproduction technique (IVF, non-IVF receiving fertility treatment at a study site, and non-IVF receiving fertility treatment at a nonstudy site) to ensure that balance between the treatment groups is maintained within site and within fertility treatment type over the enrollment period.
The study is designed with a sample size of 2,400 randomized participants based on obtaining adequate power to detect meaningful differences in the live birth rate between cohorts. Since the comparison of sperm parameters are differences between continuous assay measurements, this sample size will be more than sufficient for the primary sperm parameter comparisons. Additionally, calculations were done to demonstrate adequate statistical power when stratified analysis is to be performed (i.e., sample size distributions among the strata and their corresponding live birth RRs detected at 80% statistical power, with an alpha level of 0.05 and a total sample size of 2400 couples divided among the folic acid/zinc and placebo arms of the trial).
Data collection will include screening male and female partners for eligibility, administering baseline questionnaires, and collecting biospecimens in both partners of the couple, body measurements for both partners, daily journal reporting for male partners, medical record abstraction related to required treatment and outcome data, and semen quality of four samples collected at baseline, two, four, and six months following study enrollment. A data coordinating center (DCC) will support the trial.
The primary analysis plan is based on an "intention-to-treat" (ITT) approach comparing the two cohorts based on the randomized assignment, both overall and by treatment strata (IVF, non-IVF receiving fertility treatment at a study site, and non-IVF receiving fertility treatment at a nonstudy site).This approach will be applied to the two primary endpoints (semen parameters and live birth rate) as well as designated secondary endpoints (number of follicles, number and proportion of oocytes fertilized).
The DCC will perform periodic safety analyses and present interim reports to the Data and Safety Monitoring Board (DSMB) as requested, during the recruitment phases of the trial. It is anticipated that safety analyses will be performed every 6-12 months. The final analysis will be performed upon completion of data collection and editing in the follow-up and close-out phase of the trial. Also one full formal interim analysis is planned and the power calculations with considerations for the choice of optimal time for the analysis have been conducted.
