Male fertility is declining at a rate that cannot be accounted for by genetics:Prof Moira O’Bryan

Shahid Akhter, editor, ETHealthworld, spoke to?Prof Moira O’Bryan, Dean of Science, University of Melbourne, to find out more about the declining fertility being accelerated by environmental exposures and what can be done about it.

Male infertility scenario

I think India is like many countries, including in Australia, we have an increasing number of men who are having their children older. We have a changing environment where perhaps male fertility is declining, and we have a population that values children highly. I think we have a problem in that we have a significant population of men who are suffering from infertility, and we have a health system that perhaps is not optimal to treat that infertility.

We know that there is very compelling fact that male fertility is declining or rather sperm output is declining. It is declining quite quickly and at a rate that cannot be accounted for by genetics. So, it must be environmental factors. We know some of the factors that impair fertility, but we don't know them all. And as in research academic sector, we haven't worked out which ones are the most problematic or how they interact with each other. So that is a problem.

Male infertility: Possibility of improvement

If we can work out what the causes of infertility are, so we know, for example, some pesticides, some plasticizes can affect fertility. If we can identify what those factors are, we can remove them from the environment. So, fertility should naturally improve. I think it's in exactly the same scenario that most compounds we experience every day. So, let's say plastic sizes. When you're drinking out of a plastic cup, it won't cause sterility, but when you add it to 2100 other compounds, each of which just affects fertility a little bit and you add them up, then you might have something that causes sterility. Again, that's an opportunity, because if you can identify five of those things and remove them from our environment or our diet, you can then increase fertility.

We do have some clues, but it would be a very worthwhile investment for industry and government and universities and the research sector to tackle those questions together. And we do know, let's say we identify some plasticizers that affect male fertility to then go to a chemist and ask them, can you formulate something that is just as good at holding food or water or whatever, but won't have negative effects on fertility?

It is possible to develop those products, but as consumers, we need to help create the market for that to happen. So we know some things that definitely cause infertility. So if young men or older men even take antibiotic steroids, we know it will make them sterile, no problem. They stop taking them. Fertility will come back. We know that we talked about some toxicants like plasticizes or pesticides, some medications. We know they suppress male fertility. Again, if you remove them often, the fertility will come back.But there are huge numbers of other things that there might be a little bit of data to suggest they push down male fertility, but they haven't been tested systematically. And if you identified life is not exposure to one compound. You have a whole soup of things. We need to test compounds in combination.

Male infertility: The diminishing factor

That is a really big question. So, there's a hypothesis called male and fertility is the Canary in the coal mine of health. We know from epidemiological data that is a big group. There's lots of variation in it that infertile men do carry a higher disease burden and they do die younger than fertile men. Now, the cause of that infertility, some of them will be genetic mutations, genetic variations quite normal where it's a dysfunction in a gene that's required for male fertility. So those men will be infertile from day one, but the same genes are also involved in other parts in your body. So while fertility fails first, other areas will be affected eventually, maybe they will be accelerated by environmental exposures.

The other side of that is, we know if any other systematic illness, for eg, if someone has influenza or malaria, or even they will break their arm. It will affect the fertility. That’s because you have bigger operation of immune system, dampens down the fertility. When they recover, fertility bounces back. Sometimes it’s the environment affecting fertility, sometimes it's infertility failing first.

Male infertility: Inheritance

Now, your question about transmission to the next generation. Again, it’s a concerning area, but again, its an opportunity. We now know, sperms are much more than passing DNA to an embryo. You can think of the DNA as a hardware of a computer. That DNA will be shared with every other cell. But layered over that DNA you have epigenetics effects and that is maybe like a code on DNA and that code is affected by men’s health, or potential father’s health. If he is healthy, you have a good code. If he has an unhealthy lifestyle or he is ill, the code is not so good. That will transfer into, what will eventually become a baby. That can have long term health outcome of that child, what will become an adult. What we don’t know, even if that happens, you can’t control having influenza. If you can save a child then, that is not necessarily a bad thing. Once a child is born, if they have a healthy lifestyle, they have good food, and have regular exercise, it an change that health trajectory. But there is a long way to go to understand all of those steps.

I work on genetic infertility and many scientists come up to me saying, you can’t inherit infertility. But of course, you can. You know, genetic variations are happening all the time in the same way you can inherit kidney disease, muscle disease in the same way your parents can inherit you infertility. Sometimes you inherit from the maternal line, sometimes from the paternal line.

In vast majority of crisis. Infertility has nothing to do with what the man did. Its just good luck or bad luck.