Overweight Threats Fertility

Men's as well as women's body size matters when it comes to fertility.

New research suggests that obesity can reduce the quality of men's sperm as well as lower a woman's chances of successfully conceiving a child using in vitro fertilization.

Danish researchers found men who are overweight or obese have significantly lower sperm counts than men of normal weight. In addition, men who were underweight also had lower sperm counts compared with normal-weight men.

The study showed that overweight men who had a body mass index (BMI, a measure of weight in relation to height used to measure obesity) over 25 had a nearly 22% lower sperm concentration and 24% lower total sperm count compared with healthy weight men.

A BMI over 25 is considered overweight and a BMI over 30 is considered obese.

Underweight men who had a BMI under 20 also suffered from similar reductions in sperm counts.

"Body mass within the ideal "normal" range was associated with higher sperm concentration, higher total sperm count, and a lower percentage of abnormal sperm," write researcher Tina Kold Jensen, MD, PhD, of the University of Southern Denmark, and colleagues.

Another study by American researchers showed that obese women are also more likely to suffer fertility problems, even when their embryos are fertilized in the lab and then implanted in their wombs.