The relationship between body mass index and scrotal temperature among male partners of subfertile couples

• This study aimed to evaluate the effect of body mass index (BMI) on scrotal temperature (ST).
• Overweight and obese men have significantly higher ST than do under and normal weight subjects.
• Further assessment of the role of weight loss or gain in ST changes is warranted.

This study aimed to determine the relationship between scrotal temperature (ST) and body mass index (BMI). Data were collected from 471 male partners in subfertile couples who visited a Korean medical infertility center between March 2013 and November 2014. Participants were classified into three groups according to their BMI (<25.0, 25.0–29.9, and >30 kg/m2). Scrotal temperature index (STI)(°C) was defined as the mean left and right skin temperature difference (ΔT) between the thigh and testicle. Mean STI and standard deviation (mean±SD) of the underweight and normal, overweight, and obese groups were −1.50±0.95, −1.08±0.83, and −0.57±0.93 °C, respectively. The obese and overweight groups had higher STI than the underweight and normal groups (p<0.001). Increased BMI is associated with higher ST. To examine this causal relationship, further assessment of the role of weight loss or gain on scrotal temperature is warranted.