Date of Award

January 2014

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)


School of Public Health

First Advisor

Adrienne S. Ettinger


BACKGROUND: In population studies, one semen sample is usually collected per individual but in clinical settings it is recommended that multiple semen samples are collected per individual for analysis. The goal of this study is to estimate the size of within-person variability in semen quality parameters with the ultimate goal of figuring out how many repeat samples are needed in a semen quality study to represent this. We will also investigate how accurately one can predict semen parameter values for an individual using the long-term average as a standard.

HYPOTHESIS: We hypothesize that a maximum of 2 semen samples has enough reliability to allow us to characterize an individual as fertile or infertile in a clinical or research setting.

METHOD: This study consists of 287 men who provided a total of 654 semen samples, (range 1 to 9). Semen samples were collected over a period of about 2 years. Within-person and between-person variability was analyzed using semen parameters: sperm concentration, total sperm count, ejaculate volume, sperm morphology (% normal) and motility (% motile).

PRELIMINARY RESULTS: There were no significant differences in demographics or reproductive history according to the number of samples collected. Semen sample variation between individuals is substantial but variation within individuals ranged from 14% to 28%. Intraclass correlation values ranged from 0.72 to 0.86 signifying high reproducibilty of semen parameter values. Correlation did not diminish with time. First samples given by each individual was highly similar to their long-term within-person average.

CONCLUSIONS: Based on the results of this study, there is high reproducibility of semen parameter values and so 1 sample can provide a true representation of an individual's long-term average.


This is an Open Access Thesis.