BMI Patient condition
less than 15 seriously underweight
15 – 18.5 underweight
18.5 – 25 normal
25 – 30 overweight
30 – 40 obese
40+ morbidly obese
To calculate BMI, visit
midlandfertility.com and use the BMI
calculator in the ‘Treatments’ section.
Low BMI, conception, pregnancy and
birth
Evidence suggests that women with a very
low BMI will have problems getting
pregnant, carrying a baby to full-term and
may also experience specific problems
soon after the birth:
 women need some body fat to have
regular periods. Very low BMI can
mean that a woman’s hormone levels
are reduced and she may not have
regular periods, reducing the chance
of conceiving, naturally or with
assisted conception
 if a woman with a very low BMI does
conceive, she has a higher risk of
miscarriage and her baby has an
increased chance of a lower birth
weight and being born prematurely
 after she gives birth, a woman with a
very low BMI may experience
increased exhaustion and depression
in the post-natal period