What is BMI and How Does it Affect Fertility?

Body Mass Index or BMI can be used to provide a general indication of whether you are underweight, normal weight or overweight. Your height and weight are used to calculate your BMI. Click here for a link to an online BMI calculator.

Your body mass is made up of fat, lean mass which includes muscle, and bone. In most cases the component contributing to a high BMI comes from fat rather than muscle. A healthy BMI range for fertility is 20-25. Fertility studies have investigated BMI and outcomes for spontaneous conception and assisted reproductive treatments.

Studies have shown a raised BMI is associated with a high risk of reproductive complications in women such as menstrual dysfunction, lack of ovulation, infertility and lower conception rates. In males there is also a relationship between BMI and sperm quality, with increases in BMI (above 25+) associated with reduced sperm count, sperm concentration and semen volume.

Low levels of body fat, indicated by a low BMI (under 20) can also affect fertility and these can be addressed through the right exercise and energy balance.
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The good news is that physical activity can improve male factor fertility and the chance of conception in females. Women with a high BMI (30+) that undertake regular exercise before IVF and ICSI have a 3 fold higher chance of getting pregnant and having a baby than those who do not. A 300% increase- that is absolutely HUGE! This increase in chance of pregnancy is realised even without a significant reduction in body weight. That means that no matter what your BMI is - Exercise will improve your chances!

Exercise right to improve your chance of success.