Is low body mass index associated with semen quality?

This study investigated if body mass index (BMI) has an effect on semen quality.

They found that low BMI is associated with reduced semen quality. 

Male infertility is an increasing health problem. In many cases the cause of infertility is unknown. Lifestyle is one factor that may influence fertility. Body mass index (BMI) is used to categorize weight in relation to height. A calculation produces a number. A BMI of 18-25 is considered normal. BMI greater than 25 is considered overweight or obese (BMI 30+). BMI lower than 18.5 is considered underweight. 

Some studies suggest that BMI may affect fertility. One study showed reduced semen quality in patients with low or high BMI. However other studies have reported no link between BMI and semen quality. It is unclear if there is a relationship between BMI and semen quality.

This study included 13 clinical reports of male infertility. A total of 15, 331 patients were included. This study compared semen parameters and BMI. Semen parameters included sperm count, concentration, and motility. Patients were grouped according to BMI.  

Low BMI was associated with low sperm count and semen volume. There was no association between low BMI and sperm concentration or sperm motility. 

This study found that low BMI is associated with reduced semen quality. 

This was a retrospective analysis, meaning it was based on medical records. Some patient data was not available. There may be other important factors to consider. More investigation is needed.