Reduced male fertility may be making it even harder for couples to conceive and be contributing to low birth rates in many countries, reveals a new European Science Foundation (ESF) report launching at the IPSEN meeting in Paris.
More than 10% of couples worldwide are infertile, contributing to the growing demand for assisted reproduction techniques such as in vitro fertilisation (IVF) for which Robert G. Edwards won the Nobel Prize in Medicine last month.
Sperm counts have dropped significantly in the last 50 years in developed countries. Today, at least one in five 18-25 year old men in Europe have semen quality in the subfertile range. Testosterone levels are also declining. This is mirrored by increasing testicular cancer in most industrialised countries and more developmental abnormalities such as undescended testes. All of these factors are linked to reduced fertility and may have common origins during foetal development.
"The important impact of men's reproductive health on a couple's fertility is often overlooked," said Professor Niels Skakkebæk from the University of Copenhagen, who co-authored the report. "Women postponing motherhood have reduced fertility, and we now see that poor sperm may be making it even harder to conceive. While poor sperm may be part of the reason more couples are using IVF it may also be making those therapies less successful."
Skakkebæk continues: "We need a common strategy in Europe to target research so we can address the poor state of men's reproductive health. That this decrease in male reproductive health has occurred in just a few decades suggests it's caused by environmental and lifestyle factors rather than genetics. So it is preventable if we correctly identify the causes."
In men some lifestyle factors such as obesity and smoking can affect sperm counts, but the effects are small. In contrast, if women smoke heavily in pregnancy, a much larger fall in sperm count is likely in their sons when they grow up. Testosterone levels naturally drop as men age, which may predispose men to cardiovascular and metabolic health problems that pose large financial and healthcare issues for national governments. Low sperm counts and low testosterone levels are both associated with increased risk of early death for men.
A recent study, by Brunel University, the Universities of Exeter and Reading and the Centre for Ecology & Hydrology, shows for the first time how a group of testosterone-blocking chemicals is finding its way into UK rivers, affecting wildlife and potentially humans.
The study identified a new group of chemicals that act as ‘anti-androgens’. This means that they inhibit the function of the male hormone, testosterone, reducing male fertility. Some of these are contained in medicines, including cancer treatments, pharmaceutical treatments, and pesticides used in agriculture. The research suggests that when they get into the water system, these chemicals may play a pivotal role in causing feminising effects in male fish.
Earlier research by Brunel University and the University of Exeter has shown how female sex hormones (estrogens), and chemicals that mimic estrogens, are leading to ‘feminisation’ of male fish. Found in some industrial chemicals and the contraceptive pill, they enter rivers via sewage treatment works. This causes reproductive problems by reducing fish breeding capability and in some cases can lead to male fish changing sex.
New EU chemicals legislation, called REACH (Registration, evaluation, authorisation and restriction of chemicals) puts the onus on the chemical industry to prove that its products are safe.
Campaigners say it could be used to reduce exposure to hormone disrupting chemicals.
Elizabeth Salter Green, CHEM Trust director, said; "Chemicals that have been shown to act together to affect male reproductive health should have their risks assessed together.
"Currently that is not the case, and unfortunately chemicals are looked at on an individual basis.
"Therefore, government assurances that exposures are too low to have any effect just do not hold water because regulators do not take into account the additive actions of hormone disrupting chemicals.
"It is high time that public health policy is based on good science and that regulatory authorities have health protection, rather than industry protection, uppermost in mind."
The Science Policy Briefing 'Male Reproductive Health' is a comprehensive insight into male reproductive health with detailed research policy recommendations. It is available online at: https://www.esf.org/publications