BMI is a major determinant that influences the fertility of men and women.

Obese men produce lots of oestrogen from peripheral fat, and oestrogen has a direct effect on sperm production ((Fisher, 2014).

Males with a higher BMI often have reduced sperm count and reduced motility and sperm function, resulting in a lower fertilization rate.


Obese women have a reduced chance of conception, both from anovulation (no ovulation)

which is almost directly correlated with BMI, and even in women who ovulate (who have a bmi over 30)

the pregnancy rate per cycle is reduced and the miscarriage rate is increased. 


Being obese (BMI>30) can reduce fertility by 50%.

Pregnancy in overweight women is often associated with problems such as maternal diabetes,

high blood pressure, big babies and increased risk of caesarean section.


The good news is, however, that as soon as you get back on track with your body weight, ovulation and fertility quickly

return to normal. Even a minimal weight loss (less than 5% of body weight) can make a difference,

therefore advice with weight and its management is an important part of fertility treatment.

(Genea: World Leading Fertility, 2013)

(Women Health Info, n.d.)

© 2014 by Sarah Luskie & Madeleine Fisher created with