BMI in relation to sperm count: an updated systematic review and collaborative meta-analysis

Area of Science:

• Reproductive Medicine
• Andrology
• Public Health

Background:

• The global obesity epidemic coincides with declining semen quality.
• The relationship between body mass index (BMI) and sperm parameters is debated.
• Previous studies have yielded conflicting results regarding obesity's impact on sperm count.

Purpose of the Study:

• To systematically review and meta-analyze the association between BMI and sperm count.
• To update the evidence on how BMI affects sperm parameters.
• To investigate the risk of abnormal sperm count across different BMI categories.

Main Methods:

• Systematic literature review with meta-analysis, including unpublished data.
• Searched PubMed and EMBASE for relevant studies up to June 2012.
• Included 21 studies with 13,077 men, stratifying data by sperm count (normozoospermia, oligozoospermia, azoospermia).

Main Results:

• No significant difference in sperm concentration across BMI categories.
• A J-shaped relationship observed between BMI and the risk of oligozoospermia or azoospermia.
• Significantly increased odds of oligozoospermia/azoospermia in overweight (OR 1.11), obese (OR 1.28), and morbidly obese (OR 2.04) men compared to normal weight.

Conclusions:

• Overweight and obesity are associated with a higher prevalence of oligozoospermia or azoospermia.
• The study highlights a dose-response relationship between increasing BMI and reduced sperm quality.
• Further research is needed to determine if weight normalization can improve sperm parameters.