A small number of women make too little or none of the two hormones that make ovulation happen. When this happens it is called hypogonadotrophic hypogonadism. The hormones involved are called luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

This can happen if you lose a lot of weight or if you have a condition called anorexia.

See What happens every month to learn more about these hormones.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.