Follicle Stimulating Hormone

Follicle stimulating hormone, or FSH, is another vital messenger produced by the pituitary gland, and it works hand in hand with LH to support your reproductive system. As its name suggests, FSH stimulates the growth and maturation of follicles in the ovaries, the tiny fluid-filled sacs that each contain a developing egg. In men, FSH plays an equally important role by supporting the production of sperm within the testes. Healthy FSH levels are a positive indicator that your body's reproductive signalling is functioning well, which matters not just for fertility but for your broader hormonal balance too.

You can think of FSH as the gardener that nurtures seeds before they are ready to bloom; without adequate FSH, eggs cannot mature properly in women, and sperm production may be less efficient in men. The pituitary gland fine-tunes FSH release based on signals it receives from the ovaries or testes, when sex hormone levels are sufficient, FSH production eases off, and when they dip, it ramps up. This elegant feedback system keeps your reproductive hormones in equilibrium.

Your FSH levels can be influenced by several factors. Age is one of the most significant, in women approaching the menopause, FSH tends to rise as the ovaries gradually produce less oestrogen, and this is a perfectly normal part of ageing. Stress, being significantly underweight or overweight, and certain medications can also shift your levels. In women of reproductive age, FSH varies across the menstrual cycle, so the day your blood is drawn can affect the reading. If your FSH result is higher or lower than expected, your GP can interpret it in the context of your age, symptoms, and other hormone levels to give you a clear picture of your health.