How Do Combined Contraceptives Work?

Combined contraceptive pills delivery synthetic oestrogen and progestogen to your body, and work by overriding your natural hormone balance. This causes key changes in how your reproductive system works, altering the environment in such a way that it’s almost impossible for you to conceive.

What is conception, and how does it happen?

Conception is a complex process which will only happen if all elements come together at precisely the right time, in precisely the right environment.

Every month one of your ovaries will release a mature egg, which travels down the fallopian tubes and into the womb. You are at your most fertile at a very specific time during your cycle - the middle point, when you ovulate - which is usually between the 13th and 16th day of your cycle.

It takes just one sperm to fertilise an egg, despite there being several million sperm contained in semen. When you have sex, these sperm will travel through the cervix, into the uterus and along the fallopian tubes. When you’re at your most fertile, you may notice that your vaginal discharge becomes thin and stretchy. This is your body’s natural way of making it as easy as possible for sperm to reach your egg.

When the sperm and egg meet, usually in the fallopian tube, a single sperm will penetrate the lining of the egg. This step is known as fertilisation, and it’s the first part in the development of an egg.

Once fertilised, the egg travels into the womb, where it plants itself in the womb lining. This lining will have thickened to prepare for a fertilised egg, which it will help develop by supplying hormones that are vital for growth. This is the second stage of fertilisation. Both stages can be prevented through the supply of synthetic hormones, taken orally through combined oral contraceptives.

How do combined contraceptives stop this?

The oestrogen in combined contraceptive pills stops you ovulating because it overrides your natural hormone levels and tricks your body into thinking that ovulation has already happened. This means there’s no egg present, so there’s nothing for sperm to fertilise.

The progestogen thickens the cervical mucous, preventing it from thinning and making it almost impossible for sperm to reach the womb.

At the same time the progestogen also stops the womb lining from developing. This means that in the extremely rare case that an egg has been released and sperm has managed to reach and fertilise it, the egg can’t develop because its life source has been cut off.

Myth vs. reality

Many women are put off from the idea of using combined contraceptives because they believe one or many myths surrounding the safety of the pill. The bottom line is that the combined oral contraceptive pill will only be prescribed to you if it’s safe for you to use; your doctor won’t intentionally put your health at risk and for the vast majority of women, the benefits of combined contraceptives outweigh any risks.

Some popular myths - and the correct facts - are listed below:

The combined contraceptive pill causes cancer

This is partially true; studies have shown that using combined contraceptive pills can result in a slight but significant increased risk of developing breast cancer. However, using combined contraceptives in the long run actually reduces the risk of developing endometrial and ovarian cancers.

The combined contraceptive pill makes you fat

Some women may experience weight gain when using combined contraceptive pills, but most don’t. Some pills like Yasmin actually reduce water retention and can help you lose weight.

Using the combined contraceptive pill for a long time will make you infertile

This is categorically untrue. Many women who find it hard to conceive when they come off combined contraceptive pills either suffer from fertility issues, or they’re in their late 30s and fertility is proven to be more difficult at this stage of life.

Some experts argue that the pill can actually preserve a woman’s fertility, because it reduces the number of conditions which can reduce fertility, such as ectopic pregnancies, endometriosis and fibroids.

Visit our contraceptive pills page to find out a wide range of oral contraceptives.