When it comes to essential hormones – the two super-important whoppers for women are oestrogen and progesterone. It’s likely you’ve seen and felt the effects of both of them throughout your monthly cycle, but do you know why they’re a big deal for your body? We bring you the lowdown on both…

All about oestrogen

This is the hormone that kicks in during puberty and is responsible for the breast development, hair growth and onset of periods that happens as a girl develops into a woman. The big E helps to control our menstrual cycle and is crucial for baby-making. It’s also closely linked to our emotional well-being, protects the health of our bones and helps to keep cholesterol under control.

The main source of oestrogen is our ovaries ­­– where we produce our eggs – but we also make a small amount in our adrenal gland and fat cells.

Oestrogen levels dip up and down during the month – spiking in the middle of our cycle, trigging ovulation (the release of an egg). If an egg isn’t then fertilised, oestrogen levels drop sharply and your period starts.

There are benefits of rising oestrogen levels. When this hormone peaks, we’re likely to feel chattier, positive and mentally sharp. You’ll also feel your horniest and the most confident about your appearance. Oh-er.

High oestrogen triggers endorphins in the brain that mask pain, so schedule a dentist appointment or wax in week two of your cycle, rather than when you’ve got your period. It will hurt a whole lot less.

While there are lots of benefits to enjoy about a high level of oestrogen, there is one downside to watch out for. It can amp up anxiety, making you feel stressed and jangly.

All about progesterone

Oestrogen’s partner in crime is progesterone and is also produced in the ovaries, in the second half of a menstrual cycle. When an egg is released during ovulation the remnants of the follicle that enclosed the developing egg form a structure called the corpus luteum.

This releases progesterone and prepares the body for pregnancy if the egg is to be fertilised. If the egg is not destined to make a baby, the corpus luteum breaks down, progesterone drops and your period starts.

If the egg is fertilised, progesterone encourages the growth of blood vessels to the lining of the womb and stimulates glands that will nourish the embryo with nutrients.

Progesterone then makes sure the womb lining is all ready for the fertilised to implant and maintains it throughout pregnancy.  During pregnancy, progesterone continues to be super-important in the development of the foetus. It makes maternal breast tissue grow and strengthens the pelvic wall muscles for labour. Progesterone steadily rises in the body all the way through pregnancy until the baby arrives.

Although the corpus luteum is the major source of progesterone, small amounts are also made by the ovaries themselves, the adrenal glands and the placenta during pregnancy.

Progesterone, either alone or in combination with oestrogen, is the hormone in an oral contraceptive – the pill.  It works by preventing ovulation (tricking your body into thinking it's pregnant) making it 99% effective in preventing pregnancy.

It is low levels of progesterone that can cause irregular and heavy periods. Lack of progesterone in the bloodstream can mean the ovary has failed to release an egg at ovulation – which can happen if a woman has polycystic ovary syndrome.