Key hormones

Sex hormones are responsible for driving sexual development (puberty). The main reproductive hormones are oestrogen and testosterone.

Oestrogen causes eggs to mature in ovaries once a girl hits puberty. These are then released at regular intervals during the menstrual cycle. Testosterone stimulates sperm production in males.

Other hormones involved in the menstrual cycle include:

• Follicle stimulating hormone (FSH), causing maturation of an egg in the ovary.
• Luteinising hormone (LH) stimulating the release of the egg.
• Oestrogen and progesterone are involved in maintaining the uterus lining.

When these reproductive hormones do not work as they should, fertility problems can occur. Our understanding of these hormones and their functions means we can assist fertility, for example through in vitro fertilisation, also known as IVF.