A doctor has warned that rapidly declining sperm counts could result in humans becoming extinct.
Dr Hagai Levine led a team of researchers who analysed the sperm counts of men from North America, Europe, Australia, and New Zealand. Results showed they halved between 1973 and 2011.
Dr Levine told the BBC: “If we will not change the ways that we are living and the environment and the chemicals that we are exposed to, I am very worried about what will happen in the future.
“Eventually we may have a problem, and with reproduction in general, and it may be the extinction of the human species.”
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Dr_Microbe via Getty Images
The study suggested the rate of decline in sperm counts among men living in Western countries is continuing and possibly even increasing. Meanwhile, there was no significant decline in South America, Asia and Africa.
Having a low sperm count can make it more difficult to conceive naturally, although successful pregnancies can still occur.
Some experts were critical of the new study’s findings, noting various flaws, and added it may be too soon to draw such conclusions about human extinction.
But writing in the journal Human Reproduction Update, the study’s authors said further research is urgently needed to get to the bottom of why men’s sperm counts are declining so much.
According to the NHS, problems with sperm, including a low sperm count and problems with sperm quality, are quite common in the UK - affecting one in three couples who are struggling to get pregnant.
Prevention
The study’s authors linked a range of lifestyle and environmental factors to the problem including: endocrine disrupting chemicals, pesticides, diet, stress, smoking and obesity.
Dr Helen Webberley, who runs the online healthcare service My Web Doctor, said the results of the research were “alarming” but added there are various lifestyle changes men can make to improve sperm health.
“Few of these will come as much of a surprise: maintaining a healthy diet, limiting alcohol consumption, stopping smoking and taking regular exercise,” she told HuffPost UK.
“Having a clear overview of your reproductive health can be useful and relevant tests - such as testosterone levels and knowing your sperm count - can provide a clearer indication of the situation.”
She added: “The environmental factors are worrying and feel a little out of our control, so more research in this area would be good. There are new studies ongoing into whether anti-oestrogen medications that we use in the treatment of female breast cancer, or even the female fertility drug, Clomid, can help when used in male patients - and we have seen some encouraging results.
“Having said that, prevention is always better than cure and we, as a nation, need to accept that we can have a positive impact on our reproductive health by adjusting our lifestyle.”
Education
Professor Geeta Nargund, medical director of CREATE Fertility, said more needs to be done to educate men and boys about their fertility.
“The findings of this study are extremely important and raise public health concerns when it comes to male fertility,” she told HuffPost UK.
“It is about time that we start educating boys and men about the effects of smoking, obesity, exposure to pesticides and plastics, and sedentary lifestyle on their reproductive health.
“We also need to address the possible effects of maternal smoking and exposure to hormones in pregnancy, during a critical window of foetal testicular development.
“I urge the Department of Education to include fertility education as part of the curriculum in secondary schools, as it can help raise awareness and prevent future infertility.”
10 Things You May Not Know About Your Fertility
(01 of10)
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1. Your fertility is mostly determined by genetics, which influences how many eggs you are born with. Doctors believe that the number of eggs you have at birth determines the length of time you will remain fertile. At birth, women have about two million eggs in their ovaries. For every egg ovulated during your reproductive life, about 1,000 eggs undergo programmed cell death. Other things, such as smoking cigarettes and certain types of chemotherapy, can accelerate egg cell death and promote an earlier menopause.
(02 of10)
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2. Regular menstrual cycles are a sign of regular ovulation.Most women have regular cycles lasting between 24 and 35 days. This is usually a sign of regular, predictable ovulation. Women who do not ovulate regularly have irregular menstrual cycles. Those who do not ovulate at all may have a genetic condition called polycystic ovarian syndrome (PCOS).
(03 of10)
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3. Basal temperature charting does not predict ovulation.An older method of tracking ovulation involves taking your oral body temperature each morning before getting out of bed. This is called basal body temperature. This method is used to spot a rise in basal temperature, which is a sign that progesterone is being produced. The main problem with using this method is that your temperature rises after ovulation has already occurred. This makes it more difficult to time intercourse at an optimal time for conception. A better method is to use over-the-counter urine ovulation predictor test kits such as Clearblue Easy. These kits test for the hormone that prompts ovulation, which is called luteinizing hormone (LH).
(04 of10)
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4. Most women with blocked fallopian tubes are completely unaware they may have had a prior pelvic infection.About 10 percent of infertility cases are due to tubal disease, either complete blockage or pelvic scarring causing tubal malfunction. One major cause of tubal disease is a prior pelvic infection from a sexually transmitted disease such as chlamydia. These infections can cause so few symptoms that you may be completely unaware your tubes are affected. This is why fertility physicians will order a dye test of the tubes, called a hysterosalpingogram (HSG), if you have been trying and failing to conceive for 6 months or longer.
(05 of10)
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5. In most cases, stress does not cause infertility. Except in rare cases of extreme physical or emotional distress, women will keep ovulating regularly. Conceiving while on vacation is likely less about relaxation than about coincidence and good timing of sex.
(06 of10)
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6. By age 44, most women are infertile, even if they are still ovulating regularly. Even with significant fertility treatment, rates of conception are very low after age 43. Most women who conceive in their mid-40s with fertility treatment are using donated eggs from younger women.
(07 of10)
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7. Having fathered a pregnancy in the past does not guarantee fertility. Sperm counts can change quite a bit with time, so never assume that a prior pregnancy guarantees fertile sperm. Obtaining a semen analysis is the only way to be sure the sperm are still healthy!
(08 of10)
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8. For the most part, diet has little or nothing to do with fertility. Despite popular press, there is little scientific data showing that a particular diet or food promotes fertility. One limited study did suggest a Mediterranean diet with olive oil, fish and legumes may help promote fertility.
(09 of10)
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9. Vitamin D may improve results of fertility treatments. A recent study from the University of Southern California suggested that women who were undergoing fertility treatments, but had low vitamin D levels, might have lower rates of conception. This vitamin is also essential during pregnancy. At Pacific Fertility Center, we recommend our patients take 2,000-4,000 IU per day.
(10 of10)
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10. Being either underweight or overweight is clearly linked with lowered levels of fertility. The evidence in recent years is that obesity is clearly linked with a longer time to conception. Having a body mass index less than 18 or over 32 is associated with problems ovulating and conceiving, as well as problems during pregnancy.