Table 2.

List of studies included in the review with comments.

Reference	Study type	Comments
Bonde et al. (1998) [6]	Prospective cohort	This study challenged the use of semen analysis as a predictor for fertility, as it found that even men with semen parameters above the lower limit for normal had a chance of being infertile, albeit a lower one
Esteves et al. (2012) [5]	Review	This review critically commented on the fifth edition WHO manual guidelines for semen analysis
Guzick et al. (2001) [9]	Case control study	This study evaluated and challenged the idea of using a single threshold value to differentiate between ‘normal’ and ‘abnormal’, instead using two threshold values to separate three groups of individuals. These groups are ‘fertile’, ‘indeterminate’ and ‘subfertile’
Leushuis et al. (2014) [10]	Prospective cohort	This prospective cohort study evaluated how much more effective two semen analyses were in predicting natural conception, concluding that it did not improve prediction
Slama et al. (2002) [11]	Case control study	The study evaluated how semen parameters affected time to pregnancy in fertile couples and found an association between semen parameters and time to pregnancy
Wang and Swerdloff (2014) [3]	Review	This review discussed problems with using semen analysis as a test for male fertility and the importance of viewing the problem of infertility as a couple’s issue. They also discuss the value of a semen analysis in extreme cases like azoospermia