In the study, researchers looked at whether doing 2 consecutive tests on semen, as recommended by WHO, is the best way to diagnose male infertility accurately. They checked over 5,000 semen samples from 2,500 men who had 2 tests. Around half of the second tests agreed with the first, depending on which criteria were used. Surprisingly, some men showed different results on the second test after initially appearing normal or abnormal. The tests of sperm concentration and normal sperm shape matched well between the 2 tests, but not the sperm movement. Overall, the tests were not always great at predicting if a man's fertility status would change from the first to the second test. The study reaffirms that doing 2 semen analyses, as advised by WHO, is still important.