Association between BMI and semen quality: an observational study of 3966 sperm donors

Abstract

STUDY QUESTION What is the relationship between abnormal BMI and semen quality? SUMMARY ANSWER Underweight was significantly associated with lower sperm concentration, total sperm number and total motile sperm count, while overweight was significantly associated with lower semen volume, total sperm number and total motile sperm count. WHAT IS KNOWN ALREADY Abnormal BMI has been associated with lower semen quality, but the results remain somewhat controversial. In addition, most previous studies have focused on the influence of obesity or overweight on semen quality, and evidence on the association between underweight and semen quality is rare. STUDY DESIGN, SIZE, DURATION This research was an observational study investigating 3966 sperm donors from a large sperm bank in Wuhan city, China. These donors passed the screening for sperm donation and underwent 29 949 semen examinations between 1 January 2013 and 9 April 2018. PARTICIPANTS/MATERIALS, SETTING, METHODS BMI was categorized into four groups: underweight (<18.5 kg/m2), normal weight (18.5–24.9 kg/m2), overweight (25–29.9 kg/m2) and obese (≥30 kg/m2). Semen volume, sperm concentration, total sperm number, total motility, progressive motility and total motile sperm count were determined by trained clinical technicians. Linear mixed models were used to conduct dose–response analyses between BMI and semen quality parameters. MAIN RESULTS AND THE ROLE OF CHANCE Underweight was significantly associated with a 3.0% (95% CI: 0.1%, 5.8%), 6.7% (1.9%, 11.3%) and 7.4% (2.2%, 12.4%) reduction in sperm concentration, total sperm number and total motile sperm count, respectively. Overweight was significantly associated with a 4.2% (1.6%, 6.8%), 3.9% (0.9%, 6.9%) and 3.6% (0.2%, 6.9%) reduction in semen volume, total sperm number and total motile sperm count, respectively. Non-linear models including continuous BMI as a natural cubic spline function yielded similar results. LIMITATIONS, REASONS FOR CAUTION Our study subjects were sperm donors who are typically young and healthy, and therefore not representative of the general male population. Caution should be paid in generalizing our results to other populations. Furthermore, we did not measure the donors’ weight repeatedly along with each semen donation; instead, we only measured it once during the screening, which may cause bias due to the variations of weight across time. WIDER IMPLICATIONS OF THE FINDINGS Our study provides evidence that underweight and overweight are associated with lower semen quality, and highlights the importance of maintaining a normal weight for men. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by the Health and Family Planning Commission of Hubei Province (Grant number WJ2015MA027), the Hubei Provincial Committee of the Communist Youth League of China, and Center for Global and Regional Environmental Research at the University of Iowa. The authors declare that there are no conflicts of interest. TRIAL REGISTRATION NUMBER N/A.

Human chromatin remodeler cofactor, RNA interactor, eraser and writer sperm RNAs responding to obesity

“…Human studies have identified a series of associations of paternal BMI to birth outcome and offspring phenotype [18][19][20]. Similarly, common semen parameters have correlated with increasing BMI [4,5,12,13] and appear independent of total testosterone with the possible exception of Kruger's strict morphology [65]. Few human obesity studies have assessed epigenetic alterations.…”

“…Current sperm diagnostic tests rely on the assessment of standard semen parameters (such as sperm concentration and motility) and in some instances, DNA analysis (such as DNA fragmentation index and high DNA stainability) [10,11]. Associations between BMI and both sperm DNA fragmentation and common semen parameters, including semen volume, sperm concentration and total sperm count, have also been suggested [4,5,[12][13][14][15]. Highlighting the importance of the paternal contribution to a child's health, these have been extended to include paternal obesity associations with birth success, birth weight and a child's phenotypic traits such as metabolic health and over-all longevity [14,[16][17][18][19][20][21].…”

Adenosine accumulation causes metabolic disorders in testes and associates with lower testosterone level in obese mice

“…The rate of infertility has recently risen as has the alarming increase in obesity (Petraglia, Serour, & Chapron, 2013; Ramaraju et al, 2018). Many studies have shown that there is a correlation between male obesity and sperm count (Campbell et al, 2015; Ma et al, 2019; Ramaraju et al, 2018). Endocrine disorders, inherited, physical, or chemical factors are involved in the decline of reproductive capacity in obesity (Alves et al, 2016; Craig et al, 2017; Hayden et al, 2018; Sifakis et al, 2017).…”

“…Many studies have shown that there is a correlation between male obesity and sperm count (Campbell et al, 2015;Ma et al, 2019;Ramaraju et al, 2018). Endocrine disorders, inherited, physical, or chemical factors are involved in the decline of reproductive capacity in obesity Craig et al, 2017;Hayden et al, 2018;Sifakis et al, 2017).…”

“…Over the past few decades, the adverse effects of obesity on male fertility have been considered a health problem. Many epidemiological studies have shown that body mass index is negatively correlated with male reproductive potential (Campbell, Lane, Owens, & Bakos, 2015; Ma et al, 2019; Ramaraju et al, 2018). The mechanisms by which obesity causes a decline in reproductive capacity are complex, involving endocrine disorders, inherited, physical, or chemical factors (Alves et al, 2016; Craig, Jenkins, Carrell, & Hotaling, 2017; Hayden, Flannigan, & Schlegel, 2018; Sifakis, Androutsopoulos, Tsatsakis, & Spandidos, 2017).…”