Body mass index in relation to semen quality, sperm DNA integrity, and serum reproductive hormone levels among men attending an infertility clinic.

OBJECTIVE: To examine the association between body weight and measures of male reproductive potential.

DESIGN: Cross-sectional study.

SETTING: Fertility clinic in an academic medical center.

PATIENT(S): Four hundred eighty-three male partners of subfertile couples.

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): Standard semen analysis, sperm DNA fragmentation, and serum levels of reproductive hormones.

RESULT(S): As expected, body mass index (BMI) was positively related to estradiol levels and inversely related to total testosterone and sex hormone-binding glogulin (SHBG) levels. There was also a strong inverse relation between BMI and inhibin B levels and a lower testosterone:LH ratio among men with a BMI > or = 35 kg/m(2). Body mass index was unrelated to sperm concentration, motility, or morphology. Ejaculate volume decreased steadily with increasing BMI levels. Further, men with BMI > or = 35 kg/m(2) had a lower total sperm count (concentration x volume) than normal weight men (adjusted difference in the median [95% confidence interval] = -86 x 10(6) sperm [-134, -37]). Sperm with high DNA damage were significantly more numerous in obese men than in normal-weight men.

CONCLUSION(S): These data suggest that despite major differences in reproductive hormone levels with increasing body weight, only extreme levels of obesity may negatively influence male reproductive potential.