Determining the Relationship Between Male Waist Circumference and Male Fertility Markers

Abstract

Rates of obesity and overweight have been increasing in developing nations for decades and at the same time infertility rates have also been climbing. In the United States obesity among men above 20 years of age has more than tripled since the 1970s to over 33% in 2016 while at the same time, certain key markers of male fertility have decreased. A great deal of research has been directed towards finding links between obesity and adverse reproductive outcomes in women, such as infertility and common pregnancy complications. However the same amount of investigation has not been undertaken for men’s fertility or reproductive health more generally. Furthermore the research that has been done for men’s fertility in relation to obesity or overweight has not yielded clear results. The most commonly used clinical measurement of adiposity is body mass index (BMI), derived by dividing an individual’s mass in kg by their height in meters squared (kg/m2). Using a BMI chart or calculator, a clinician can categorize patient’s weight as “normal” (18.5 to < 25), “underweight” (<18.5) “overweight” (25 to < 30) or “obese” (≥30). This makes for a useful clinical measure, both easy to obtain and well known to be positively correlated with patient fat mass. However BMI is also positively correlated to lean mass, and suffers from an inability to factor in weight distribution. Another clinical measurement of adiposity, waist circumference (WC), a measurement that has been more closely linked to some adverse health trends than measures of mass or BMI may be a better proxy for central adiposity. Research that examines the link between central obesity as measured by WC and male fertility is limited. To examine the relationship between WC and markers of male infertility I analyzed WC and fertility markers in 682 semen samples from 276 men undergoing assisted reproductive treatment for infertility. By analyzing anthropometric data and creating generalized linear models to estimate semen quality parameters based on WC tertiles, I was able to determine that in couples seeking reproductive therapy, WC is inversely related to sperm concentration and total sperm count.