Men who smoke heavily may impair sperm, fertility

October 17, 2005

BUFFALO, N.Y. -- Men who smoke cigarettes may experience a significant decline in their capacity to father a child, research by a reproductive medicine specialist from the University at Buffalo has shown.

Sperm from nearly two-thirds of the chronic smokers in the study failed a special test that measures the ability of sperm to fertilize an egg. On average, those men showed a 75 percent decline in fertilizing capacity when compared to nonsmokers. Lead researcher Loni Burkman, Ph.D., presented the results today (Oct. 17, 2005) at the American Society of Reproductive Medicine annual meeting in Montreal, Quebec.

Burkman is associate professor and head of the Section on Andrology, Department of Gynecology and Obstetrics in the UB School of Medicine and Biomedical Sciences and an assistant professor of urology.

"Like other cells in the body, human sperm carry a receptor for nicotine, which means they recognize and respond to nicotine," said Burkman. "This happens because nicotine from tobacco mimics one of the most important neurochemicals produced in the body. "Using sperm of nonsmokers, we reported previously that the addition of nicotine changed three sperm functions required to fertilize an egg.

"In this new study, we examined whether sperm from chronic tobacco smokers are defective in binding to the zona, the cover surrounding an egg," said Burkman. "Our results could mean that heavy smoking overloads the nicotine receptor in human sperm and in the testes, leading to a decline in fertilizing potential."

The study involved 18 men who reported smoking at least four cigarettes a day, every day, for more than two years. On average, these men had smoked for about 15 years. Their sperm function was compared to that of non-smoking donors who served as controls and whose fertilizing capacity had been confirmed.

Using a test called the Hemizona Assay developed by Burkman, the researchers cut a zona in half, placing one half with a smoker's sperm and the matching half with control sperm. After two to three hours of incubation, researchers counted the number of sperm attached tightly to the outside of each half.

The number of attached sperm from the smoker was compared to the control number, which gave a ratio or index. The Hemizona Assay has been shown to predict fertilization failure during in vitro fertilization.

"To fail, the index must be less than 65, meaning that the smoker's sperm had less than 65 percent of the fertilizing capacity found in the donor," Burkman said. "An index below 36 identifies a severe loss in fertilizing capacity."

Results showed that the sperm from almost two-thirds of the smokers failed the test, while the remainder showed normal function. Almost all the smokers whose sperm failed the test had an index of 36 or less, with an average of 25.

"None of these men had a zero fertilizing potential," said Burkman, "but the results mean that their sperm had only 25 percent of the fertilizing function found in nonsmoking men. The data also showed that the men who failed were smoking about twice as many cigarettes per day, an average of 19 per day, compared to the smokers who passed the assay."

As another way to understand the impact of smoking, the researchers calculated a "smoking load" for each smoker by multiplying the number of cigarettes smoked per day by the number of years smoked. The load varied from 16 to 750 for the 18 men.

Results showed that the men who smoked fewer cigarettes for fewer years had smaller smoking loads, ranging from 16 to 200. In this group, 71 percent passed the Hemizona Assay, indicating normal fertility. The remaining men had a high smoking load, and only 18 percent passed the assay.

"Specialized testing clearly reveals a significant drop in fertility potential for men who are heavy tobacco smokers," said Burkman. "Smoking men also should be aware that smoking can damage their sperm DNA, passing on faulty DNA to their baby. Concerned smokers should quit or be tested in a local andrology laboratory."
Burkman added that other scientists have shown a similar decline in fertility among women who are heavy smokers. Roxanne Mroz and MaryLou Bodziak, UB research associates, contributed to this work, along with UB undergraduate students Stuti Tambar, Brian Telesz, and Scott Beardsley.

The research was funded by the Philip Morris External Research Program.

The University at Buffalo is a premier research-intensive public university, the largest and most comprehensive campus in the State University of New York.

University at Buffalo

Related Smoking Articles from Brightsurf:

Smoking rates falling in adults, but stroke survivors' smoking rates remain steady
While the rate of Americans who smoke tobacco has fallen steadily over the last two decades, the rate of stroke survivors who smoke has not changed significantly.

What is your risk from smoking? Your network knows!
A new study from researchers at Penn's Annenberg School for Communication found that most people, smokers and non-smokers alike, were nowhere near accurate in their answers to questions about smoking's health effects.

Want to quit smoking? Partner up
Kicking the habit works best in pairs. That's the main message of a study presented today at EuroPrevent 2019, a scientific congress of the European Society of Cardiology (ESC).

Smoking and mortality in Asia
In this analysis of data from 20 studies conducted in China, Japan, South Korea, Singapore, Taiwan and India with more than 1 million participants, deaths associated with smoking continued to increase among men in Asia grouped by the years in which they were born.

Predictors of successfully quitting smoking among smokers registered at the quit smoking clinic at a public hospital in northeastern Malaysia
In the current issue of Family Medicine and Community Health, Nur Izzati Mohammad et al. consider how cigarette smoking is one of the risk factors leading to noncommunicable diseases such as cardiovascular and respiratory system diseases and cancer.

Restaurant and bar smoking bans do reduce smoking, especially among the highly educated
Smoking risk drops significantly in college graduates when they live near areas that have completely banned smoking in bars and restaurants, according to a new study in the American Journal of Epidemiology.

How the UK smoking ban increased wellbeing
Married women with children reported the largest increase in well-being following the smoking bans in the UK in 2006 and 2007 but there was no comparable increase for married men with children.

Smoking study personalizes treatment
A simple blood test is allowing Vanderbilt University Medical Center (VUMC) researchers to determine which patients should be prescribed varenicline (Chantix) to stop smoking and which patients could do just as well, and avoid side effects, by using a nicotine patch.

A biophysical smoking gun
While much about Alzheimer's disease remains a mystery, scientists do know that part of the disease's progression involves a normal protein called tau, aggregating to form ropelike inclusions within brain cells that eventually strangle the neurons.

A case where smoking helped
A mutation in the hemoglobin of a young woman in Germany was found to cause her mild anemia.

Read More: Smoking News and Smoking Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to