Low testosterone in primary infertile men is associated with a history of maternal obesity during pregnancy: Findings from a cross-sectional study.

Background: Maternal obesity increases offspring obesity risk, but limited data exist on its association with reproductive hormones in infertile males.

Objectives: To investigate the impact of maternal obesity during pregnancy on total testosterone levels in primary infertile men.

Materials and methods: Data from 418 men seeking medical help for primary infertility were analyzed. Demographics, clinical data, comorbidities, and history of maternal obesity during pregnancy were recorded. Testicular volume was assessed with Prader's orchidometer. Serum hormones, including calculated free testosterone, and semen parameters were collected. Low testosterone and low calculated free testosterone were defined as total testosterone <3 ng/mL and calculated free testosterone <120 pg/mL. Descriptive statistics and regression models evaluated associations between maternal obesity at pregnancy and both total testosterone and calculated free testosterone levels.

Results: Median (interquartile range) age and body mass index were 36 (33‒40) years and 24.8 (23.1‒26.8) kg/m². Men with low testosterone (n = 69) had higher body mass index, Charlson comorbidity index score, and follicle-stimulating hormone, but lower testicular volume, sex hormone-binding globulin, sperm concentration, motility, and normal morphology compared to men without low testosterone (all p < 0.04). Similarly, men with low calculated free testosterone (n = 226) showed higher sex hormone-binding globulin, lower estradiol, sperm concentration, and motility than those with normal calculated free testosterone values (all p < 0.02). Low testosterone (7.2% vs. 2.0%, p = 0.01) and low calculated free testosterone (4.4% vs. 1.0%, p = 0.03) were more frequently reported during maternal obesity. Multivariable logistic regression analysis showed that maternal obesity at pregnancy (odds ratio: 5.9), higher body mass index (odds ratio: 1.1), and lower testicular volume (odds ratio: 0.9) were independent predictors of low testosterone (all p < 0.01), adjusting for age. Multivariable linear regression analyses identified maternal obesity at pregnancy (β = ‒4.1) and lower testicular volume (β = 1.8) as independent predictors of calculated free testosterone (all p < 0.001), after accounting for age and body mass index.

Conclusions: Low testosterone is a frequent characteristic in primary infertile men. Although rare, maternal obesity at pregnancy is significantly associated with reduced total testosterone and calculated free testosterone levels. Further preventive strategies and close follow-up should be considered in this specific group.