How does the combination pill actually work?

Time to break down the facts around taking the pill.
Written by
Team Kin
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Last updated on
June 4, 2024
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How Does the Combined Pill Actually Work? | Kin Fertility
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The combination pill, or the pill for short, is one of the most commonly used forms of contraception — data from 2013 shows that in Australia alone, 27-34% of women use oral contraception [1].

Before you start taking combination pills, it's worth understanding what it does to your body and how it works to prevent pregnancy so you know you're choosing the right contraception for you.

We've looked through the research, read the articles and delved into first-hand case studies to tell you what happens to your body when taking the combined oral contraceptive pill.

What is the combined pill?

The combined pill is made up of two hormones — oestrogen and progestogen — which are similar to the ones your body makes in the ovaries [2]. In Australia, most brands of combined oral contraceptive pills include different types and doses of these hormones.

For example, some pill packets can contain 21 hormone pills (also known as the active pill) and 7 pills without hormones, while others contain 24 active pills and 4 inactive pills [2].

How does the combined pill work?

The most commonly told story about how the combined pill works is that it makes your body think it's pregnant. While we’re not entirely convinced that it’s an accurate summary of the intricacies of the female menstrual cycle, it does have some truth to it.

To break it down into simple terms: progesterone and oestrogen in your pill suppress the (big words coming up) Follicle-Stimulating Hormone and Luteinizing Hormone.

While these sound scary, they are actually some of the most natural hormones in the female body and are the two big contributors to triggering ovulation. When you block or alter these hormones, you can stop ovulation and this is what the progesterone and oestrogen in combination birth control pills do.

Editing the hormone balance in your body can make it think that it doesn’t need to release Follicle-Stimulating Hormone and Luteinizing Hormone and therefore doesn’t need to ovulate.

This means that the birth control pill stops the ovaries from releasing an egg each month, while also causing the mucus in the cervix to thicken so that sperm can't find its way in there [2].

As this is similar to what happens during pregnancy (progesterone and oestrogen spike and ovulation stop) people sometimes like to say that the body is tricked into thinking it’s pregnant.

Does the combination pill give you an artificial cycle?

If you’re already on the combined pill, you’ll notice that you still bleed as if you’re having a period, however, the truth is that the combined pill gives you an artificial cycle.

In essence, the constant high levels of progesterone and oestrogen replace the natural cycle, which is then broken by a week of placebo pills. At that point, you have a breakthrough bleed that mimics the real bleed that occurs during a natural cycle.

This bleed is actually a withdrawal bleed, occurring because the progesterone and oestrogen in your body drop, causing the lining of the uterus to shed. This artificially induced period usually feels, looks, and seems exactly like a normal period but may be a little lighter.

If you're ever curious about how your cycle might be affected by all this, it can always help to keep track of it using an app, or an old-fashioned calendar. And, don't worry, you can take the pill continuously and skip your period when needed.

Do you ovulate on the combined pill?

No. The combined pill stops ovulation and therefore prevents you from being able to get pregnant.

The main thing that the combined pill actually does to your body is top up the progesterone and oestrogen that stops the natural cycle in which your body prepares for egg release. In doing that, you shouldn’t ovulate and therefore shouldn’t get pregnant.

How effective is the combination pill?

If used correctly, the birth control pill is 99.5% effective [2]. On the occasions you forget to take your pill, it hovers around 93% effective.

In saying that, nearly 1 in 10 women taking the pill may still get pregnant so it's not completely foolproof [3]. And, it's important to note that the contraceptive pill may not work if you have diarrhoea or vomiting and certain medications can affect its accuracy so be sure to check this with your doctor.

Can I take my combination pill any time?

Unfortunately not. For the pill to be effective at preventing pregnancy, you must take it at the same time every day, or as soon as possible. While it might sound fussy, taking it at different times of the day can affect the effacy of the contraception.

It can be helpful to set an alarm on your phone as a reminder. As soon as it goes off each day, it's time to take the pill!

In the instances that you forget to take the pill, be sure to take it as soon as you remember and take the next pill at your usual time the next day [3]. If you take the pill more than 24 hours late, you are at risk of getting pregnant.

If you want to learn more about how to manage your pill, Kin Fertility has your back. Kin's pill subscription allows you to access the combination pill without needing to leave your home.

You'll undergo a digital consult and an Australian practitioner will create a prescription plan for you, which is sent straight to your door. Yep, this means no visits to a doctor's office, no trips to the chemist and no forgetting to refill your prescription.

All of the tools you need to take your reproductive health into your own hands.