Follicle Stimulating Hormone (FSH)
Stimulates your ovaries to produce oestrogen. FSH and oestrogen work together to grow and develop the eggs in your ovaries. As oestrogen drops, FSH actually rises in response. This rise in FSH level in the blood can be used as a test to understand if you are perimenopausal. Any FSH blood tests need to be repeated twice over a 6-8 week period, to confirm whether the levels are high.