For couples considering having children, there may be one more reason to slim down! A new study shows that a man’s weight may affect a couple’s chances at conceiving. Dr. A Ghiyath Shayeb, from the University of Aberdeen, Aberdeen, UK, has determined that men with a higher body mass index (BMI) face difficulties when trying to have children.

The researchers found that obese men may have lower volumes of seminal fluid and a higher proportion of abnormal sperm. In addition, obesity is a known risk factor for women trying to conceive. As such, researchers are exploring the possibility of a link between male obesity and the difficulties in conceiving. 

Dr. Shayeb and his fellow researchers searched for any link between BMI and semen quality. Specifically, they examined the results of seminal fluid analysis for 5,316 men experiencing problems with conception, along with their partners. The subjects were divided by their BMI scores into four groups, ranging from being “underweight” to “considerably overweight.” Other characteristics that may have influenced the analysis were taken into account, including: smoking, alcohol intake, age, social deprivation, and the length of time of abstinence from sex prior to producing a semen sample for analysis.

The Study’s Findings Explained

It was shown that those subjects with an “optimal” BMI score of 20-25 — as classified by the World Health Organization (WHO) — displayed the optimal benefits for conception. Compared to the other subject groups, these subjects had higher levels of normal sperm and higher semen volume. However, no significant difference in sperm concentration or motility was found among the four BMI groups.

While all of the subjects underwent at least one routine semen analysis, any DNA damage among the patients was left unexamined. This may be because many other studies have already illustrated the link between male obesity and reduced fertility, due to increased DNA damage in the sperm. “Our findings were quite independent of any other factors, and seem to suggest that men who are trying for a baby with their partners, should first try to achieve an ideal body weight,” said Shayeb. “This is in addition to the benefit of a healthy BMI for their general well being. The doctor continues: “Adopting a healthy lifestyle, a balanced diet, and regular exercise will — in the vast majority of cases — lead to a normal BMI. We are pleased to be able to add improved semen quality to the long list of benefits that we know are the result of an optimal body weight.”

Further Research in the Works

In the future, the research team plans on following up their findings. They plan on comparing male BMI in fertile and infertile couples to determine whether poorer semen quality is associated with reduced fertility. Dr. Shayeb adds that his team hopes to address exactly how obesity affects semen production. “The mechanism for the relationship could be a number of things - different hormone levels in obese men, simple overheating of the testicles caused by excessive fat in the area, or that the lifestyle and diet that leads to obesity could also lead to poorer semen quality. We just don’t know the answer yet, but this is an important question that needs urgent attention.”