News ID: 132842
Published: 0333 GMT December 14, 2015

Environmental, lifestyle factors tied to infertility in men

Environmental, lifestyle factors tied to infertility in men

Environmental and lifestyle factors are damaging men's reproductive health and may be playing a large role in decreasing fertility rates in industrialized countries, according to a new study.

A team of experts in reproductive medicine from Denmark, Finland and the US reviewed the available population and animal studies on reproductive health, examining incidences of testicular cancer and male organ development disorders, testosterone level, sperm quality, ratio of male-to-female children born, frequency of childlessness and demand for assisted reproductive techniques. The researchers examined factors that could affect reproductive health: Gene mutations, which are changes in the gene caused by alterations in the DNA code; gene polymorphisms, which are variations of the same gene; epigenetic changes, the alteration of the gene due to changes in how the DNA code is read; and environmental and modern lifestyle factors, including exposure to chemicals, occurrence of traumatic events, fitness and nutrition, said.

The analysis showed that poor semen quality contributed to increases in infertility and use of assisted reproductive technology. It also revealed higher incidences of testicular cancer worldwide with the greatest frequency in countries with Caucasian populations. Lower levels of testosterone in men and increased occurrence of congenital abnormalities of reproductive organs in male newborns were also observed.

"I was surprised that we found such poor semen quality among young men ages 20 to 25," said lead researcher Niels Skakkebaek of the University of Copenhagen in Denmark. "We found that the average man had more than 90 percent abnormal sperm. Normally, there would be so many sperms that a few abnormal ones would not affect fertility. However, it appears that we are at a tipping point in industrialized countries where poor semen quality is so widespread that we must suspect that it results in low pregnancy rates."

Many of the male reproductive problems could be detected in utero. While the reproductive problems could arise from genetic changes, recent evidence suggests that most often it is related to environmental exposures of the fetal testis, the researcher team wrote.

"Since the disorders in male genitals are increasing in a relatively short period of time, genetics cannot explain this development," Skakkebaek said. "There is no doubt that environmental factors are playing a role and that endocrine [hormone]-disrupting chemicals, which have the same effect on animals, are under great suspicion. The exposure that young people are subjected to today can determine not only their own, but also their children's, ability to procreate."


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