Sperm Morphology: New Guidelines Announced: 4% is Normal
Posted Jul 01 2010 4:25am
Wow, what a relief to know that what we have been saying for years is now finally officially stated. Any sperm morphology over 3% is considered normal.
How did this change come about? The World Health Organization (WHO) determines the normal parameters for semen including volume, count, motility, forward progression and morphology. The WHO published their guidelines in 1987, with updates in 1992 and 1999. The original “normal” cutoffs were based on estimates from old data, some of it dating back to the 1950’s. There were inconsistencies in the way data was collected, ie the sperm studied was collected and analyzed in many centers, but there was little regulation of how the tests were being performed. Plus there was not clear data on the history of the men.
This time the semen tests were performed using similar protocols in all of the testing centers. Plus, some history was obtained from the men, mostly related to fertility status.
4500 men in 14 countries on 4 continents were tested. Australia, China, Denmark, Germany, Chile, Singapore, France, the UK, and the USA were some of the countries included.
Men were placed into one of 4 groups. Fertile men. All men in this group had initiated a pregnancy sometime in the 12 months preceding testing. This was the most important group because the researchers could establish normal values based on men know to have fertile sperm. There were 3 other groups evaluated. To save a little confusion, I’ll summarize and say 2 groups were a little more random in nature and the fertility status of the men was mostly unknown. The 4th group was also fertile, but the time since last pregnancy was unknown and may have been longer than 12 months.
The results. The normal fertile men’s sperm had the following results. Volume: The median (midway between the lowest and highest results) was 3.7 cc, but anything over 1.5 cc was considered normal Concentration: the median was 73 million but anything over 15 million was considered normal Motility: the median was 61%, anything over 40% being normal Morphology: the median was 15%, anything over 3% was deemed normal.
Some important points. You may have noticed that morphology is not the only parameter with a new normal value. Volume was at 2.0 cc, now it is at 1.5cc. A normal count was 20 million, this changed to 15 million. Motility was 50%, now it’s 40%. The normal morphology had the biggest change, as it went from 15% to 4%.
Keep in mind that in this group, all of these men were fertile, so even men with levels lower than the new definition of normal had working sperm. The normal values were established mathematically. If you were in the upper 95% of the fertile people you were deemed normal. The bottom 5% of the fertile people was deemed abnormal. This 95%/5% cutoff is the system used to define cut offs for other tests such as TSH, Prolactin and many others.
When comparing the different groups of men there were very slight differences in volume, count, etc, but hardly worth mentioning. Fertile men did have slightly higher volume and counts then men whose fertility status was unknown. Morphology was mostly similar in the different groups. Remember, there was no group of men who had established infertility, so in this study there is no way to compare normal fertile men to known infertile men.
And even though we have no details on the women, knowing that they became pregnant in the past year is probably all the information we need.
So now you know. Any morphology over 3% is considered normal. If your doctor tells you otherwise, ask him if he has seen the new WHO guidelines.
To take it one step farther, can there really be difference between 4% and 2%? I doubt that there is a difference between having 96% abnormally shaped sperm and 98% abnormally shaped sperm. So as I have said before, at our practice here at NYU, morphology is not considered with much respect, except in some rare cases where the sperm is unusually abnormal.
I hope this helps.
For those of you who want more details, here is the link.