Markku Sallmen就职于芬兰职业卫生研究所。他说：“数据显示，男性体重每增加20磅（约9公斤），不育的可能性将增加10%。”体重指数是由人的体重和身高计算得来的数据，对大多数人，体重指数可成为身体肥胖的可靠指标，也常被用来筛查体重超重。
研究者对农业卫生研究计划中注册的夫妇进行了研究。这项始于1993年的计划目的是为了检测影响农业社区农民及其家人健康的因素。
国立环境卫生科学研究所的流行病学家Donna Baird博士说：“与体重正常的妇女相比，超重或肥胖的妇女较难怀孕，但是同样情况的男性是否存在生育问题尚未有人研究。”这项结果发表在2006年9月《流行病学杂志》上。
不育和体重指数的数据资料来源于1468位农民和他们的妻子在登记纳入这项研究时完成的问卷调查。后者完成家人健康调查表，包括夫妇的生育史，前者报告家人体重和身高的调查表。研究分析限于登记注册4年前打算生育及女方年龄低于40的夫妇。
研究者将这些夫妇分为不育组和可育组，超过1年未受孕者归为不育组，在1年内受孕者归为可孕组。大多数男性和女性年龄超过30岁，28%的夫妇有不育症状。
研究者发现男性的体重指数是不育症的独立危险因素。研究员调整了其它影响生育力的因素，如女性的高体重指数、年龄、吸烟、饮酒、暴露于杀虫剂，调整过后，随着体重指数的增加，不育呈线性增加，在肥胖男性，不育率增加1倍。研究者还发现无论年龄大小，男性的体重指数都是不育症的危险因素。
虽然没有性交频率的数据，但据推测超重的男性较体重正常的男性性交次数少，从而影响了生育。然而，关于精子特性的研究发现超重和肥胖的男性，精子质量较低，激素不平衡。
国立环境卫生科学研究所的主任David A. Schwartz博士说：“这项研究提出了某些与肥胖有关的另外的健康问题，抑制肥胖可促进男性身体健康，其中就包括他们的生殖健康。”该研究所还提出了一项新的战略性的计划——“环境科学和人类健康的新前沿”，这项计划将于明年5月实施，目的在于利用环境卫生科学促进公众了解疾病的发病原因并促进人类健康。
Men with increased body mass index (BMI) were significantly more likely to be infertile than normal-weight men, according to research conducted at the National Institute of Environmental Health Sciences (NIEHS), one of the National Institutes of Health.
"The data suggest that a 20-pound increase in men's weight may increase the chance of infertility by about 10 percent," says Markku Sallmen, lead author on the paper who is now at the Finnish Institute of Occupational Health. BMI is a number calculated from a person's weight and height. BMI provides a reliable indicator of body fatness for most people and is used to screen for weight categories that may lead to health problems.
The researchers studied couples enrolled in the Agricultural Health Study (AHS), a large project that began in 1993 examining factors that impact the health of farmers and their families in agricultural communities.
"Women who are overweight or obese tend to have a more difficult time becoming pregnant than normal-weight women, but whether men who are overweight or obese also have fertility problems had not been studied," says Donna Baird, Ph.D., an NIEHS epidemiologist with the study. The study is published in the September 2006 issue of Epidemiology.
The data on infertility and body mass came from questionnaires that 1,468 farmers and their wives completed when they enrolled in the study. The wives completed a family health questionnaire, which included information about the couple's reproductive history. The men reported their weight and height on a questionnaire about their health. The analysis was limited to couples with a pregnancy attempt during the four years before enrollment, and to women under the age of 40.
The researchers divided the couples into infertile and fertile groups. The infertile couples were those that tried for longer than a year to conceive, and the fertile couples were those that conceived within a year. The majority of men and women were more than 30 years old. Twenty-eight percent of the couples had experienced infertility.
Researchers found that men's BMI was an independent risk factor for infertility. The researchers adjusted for other factors that could affect fertility, including high BMI of the woman, age, cigarette smoking, alcohol intake, and solvent and pesticide exposure. After adjustment, there was a general increase in infertility with increased BMI, reaching a nearly 2-fold increase among obese men.
When researchers divided the sample into two equal groups by men's age, they found that men's BMI was a risk factor for infertility in both the older and younger men.
The researchers did not have data on frequency of sexual intercourse, so it is possible that overweight men have less sexual intercourse than their normal weight counterparts and this could influence fertility. However, there have been recent studies looking at semen characteristics that show lower semen quality for overweight and obese men, as well as hormonal differences.
"This study provides data on some additional health problems associated with obesity," said David A. Schwartz, M.D., director of the National Institute of Environmental Health Sciences. "Preventing obesity can help improve men's overall health, perhaps even their reproductive health."
The NIEHS unveiled a new strategic plan, "New Frontiers in Environmental Sciences and Human Health," in May aimed at challenging and energizing the scientific community to use environmental health sciences to understand the causes of disease and to improve human health.
来源于http://www.news-medical.net/?id=19763
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