Reviewed by

Rebecca Verhofstede - Midwife & Menstrual Health Expert


How birth control works

Reviewed by

Rebecca Verhofstede - Midwife & Menstrual Health Expert

How to Figure Out Which Birth Control Method is Right For You. There are few things harder in life than figuring out which birth control option is right for you. How does birth control work? While they all ultimately do the same thing, the way they work is very different. How can you possibly know which one is right for you? In this blog post, we’re going to break it down for you. We’ll talk about the four most important hormones: estrogen, progesterone, FSH and LH. We’ll also talk about each of the different birth control methods and how they work. Let’s dive in, shall we?

Hello Hormones!

Before we get into the nitty gritty, you need to know the basics about how birth control works. 

Your cycle can be divided into two phases: the phase before you ovulate (follicular phase) and the phase after you ovulate (luteal phase). In between these phases, you ovulate and this is when you are most fertile.

There are four major players in this process:


Estrogen is the leading lady in the first half of your cycle. This is the hormone that causes the lining of your uterus to thicken making it the perfect home for a fertilised egg.

It also produces sperm-friendly mucus that makes it easier for the little swimmers to reach the egg and do their job.

As ovulation approaches, your body produces more estrogen which causes you to create a smooth, white discharge. Once you’re looking for this so-called cervical mucus, it can be very obvious and it’s a sign that your body is primed and ready to make a baby (if that’s what you’re hoping for).


In Act 2 of your cycle, progesterone takes centre stage as estrogen takes a back seat.

This is the hormone that helps implant a fertilised egg. It also ensures your body is ready for this process to occur.

But, if there is no fertilised egg, progesterone decreases and the lining of your uterus starts to break down. This is the start of your period.

Supporting Actors: FSH and LH

Estrogen and progesterone tend to hog the spotlight when it comes to your cycle, but there are actually two other lesser known hormones that play a supporting role in the process: follicle-stimulating hormone (FSH) and luteinizing hormone (LH).


There’s a gland in the middle of your head called the pituitary gland. This gland is responsible for many hormones, including the follicle-stimulating hormone (FSH).

This hormone does what it says on the tin: it stimulates the follicles.

Why is this important? Well, the follicles are the sacs where an undeveloped egg will develop, so it’s kind of a big deal.

Put simply, this is the hormone that helps your ovaries prepare your eggs. Think of it like a super helpful assistant that helps get everything ready behind the scenes. In each cycle, a number of follicles will develop and over time, one will become dominant. This is the follicle that will grow into an egg and eventually, make its way to your uterus.

And Last but Not Least… LH

The luteinizing hormone (LH) increases alongside estrogen in your body. This increase causes the follicle to break open and BAM! A mature egg is released.

This is called ovulation and it'sits when a mature egg makes its way into your fallopian tube. Your most fertile days coincide with a spike in your LH. That’s why so many ovulation trackers report on this hormone. If you’re trying for a baby, pay attention to your LH level. It only lasts one or two days so make sure you’re having sex during this time to maximize your chance of getting pregnant.

Now you know how birth control works. 

What Are My Birth Control Options?

If you have trouble deciding on what food to order at a restaurant, it's no wonder that choosing a birth control method can send you into a tailspin. There’s a lot of options and each one works in its own way so it’s natural that you might have questions like what does birth control do to my body? 

The two best known options are the pill and the hormonal IUD.

But, there’s also birth control methods that don’t interfere with your hormones: the copper IUD and, of course, going with nature and using a natural fertility method.

Here’s the low down on each option to help you decide what works best for you…

The Pill

You’re probably already familiar with the pill. It’s a small tablet you take every day. It’s simple, convenient and effective, as long as you remember to take it every day!

But how do birth control pills work? They work by releasing artificial hormones which prevent ovulation.

The pill creates artificial progesterone which stops your body from releasing LH and FSH. This stops you from ovulating which means you can’t get pregnant. It also means that there’s nothing to release so you don’t really get your period when you’re on the pill.

Wait a second, I hear you say... Don’t you still bleed every month when taking the pill? Yes, you do, but the monthly bleeding is artificial. During the 7 days where you stop taking the pill, the artificial hormones are not absorbed and the lining that was built up, is broken down again. This is called withdrawal bleeding.

The pill also causes the lining of the cervix to change. The mucus becomes tough and cloudy which makes it tough terrain for the sperm to cross!

Pill Problems

While the pill is highly effective and one of the most widely used birth control methods among women in the world, it does have some downsides.

While the negative effects of the pill have been downplayed for years, they are getting more and more attention lately. And, for good reason: the pill can reduce your sex drive. (boo!)

The pill also changes the supply of vitamins and minerals in your body which can cause a whole variety of issues such as tiredness and even depression. So, if the pill is still your birth control method of choice, it’s important to take supplements that help ensure your vitamin and mineral levels are balanced.

Does the pill affect your fertility? 

Taking a small pill every day that alters natural processes in your body is bound to make you wonder about the long term effects. After all, many women take the pill for many years. And, when you do decide to stop taking the pill, does it affect your fertility? 

There is no evidence to suggest that taking the pill affects fertility. There is also no evidence to suggest that your natural cycle will be delayed or impacted when you decide to stop taking the pill. While every woman is different, most will have a natural period 2-4 weeks after they stop taking the pill. It’s important to remember that your first period after coming off the pill is known as a “withdrawal bleed.” Your next period will be a natural one. 

Many women notice that their periods are irregular after they stop taking the pill. This is very common and not necessarily something to worry about. For many women, it can take several months to return to a natural cycle. 


The IUD is a small device that is inserted into you by a doctor or gynaecologist. Unlike the pill, the IUD is a “one and done” approach where once it’s in, it works for up to 10 years!

It works by preventing the egg from implanting into the uterus.

There are two options: the hormonal birth control IUD and the copper IUD.

The Hormonal IUD

This IUD releases progesterone which impacts your endometrium, the lining of the uterus. It makes it hard for sperm cells to get through the cervix and a fertilized egg cannot implant successfully.

While the chance of pregnancy with the hormonal IUD is very small, ovulation does sometimes still occur.

And while only a small amount of hormones is released into your body with the IUD, many women do report some problems like acne, mood swings, feeling bloated and loss of sex drive.

The Copper IUD

Unlike the Hormonal IUD, a copper IUD does not contain any artificial hormones and it is a very reliable form of birth control.

It works in two ways:

  • Look out sperm! Copper is toxic to sperm! So, any sperm that gets through cannot fertilize an egg.

  • Copper is also a total homewrecker for a fertilized egg. It makes the lining of the uterus completely inhospitable so a fertilized egg is left homeless with nowhere to go!

Unfortunately, many women experience complaints with the copper IUD as it causes inflammation with severe cramps and bleeding as a result.

But wait… there’s more

And as if deciding between the pill, the hormonal IUD and the copper IUD wasn’t enough, there’s other methods of birth control worth considering.

There’s also the contraceptive patch and ring and the contraceptive implant. All three use hormones so the effect is the same as the pill or the hormonal IUD.

Going Au Naturel

You don’t have to rely on the pill or an IUD. There are natural ways to avoid pregnancy but be aware: they can be prone to human error. And, while birth control effectiveness varies depending on the method, so-called “natural fertility planning” has the greatest likelihood of surprising you!

But, if you’re trying to have a baby, natural fertility planning can also be a big help too.

It works in two ways:

  • By measuring your basal body temperature.
  • By analysing your cervical mucus.

Feeling hot, hot hot!? That’s because when you ovulate, your temperature rises by 0.2 – 0.3 degrees. A rise in temperature can therefore tell you that you’re ovulating!

To do this accurately, you’ll need a thermometer that shows two decimal places (ie: 37.43 vs. 37.4). You can track this data the old fashioned way (pen and paper!) or through an app. There are dozens to choose from.

You can also track the changes in your cervical mucus. Don’t worry: there’s no need for a science experiment. Simply look at the discharge in your underwear and examine the colour and consistency. During your cycle, it will generally be sticky and cloudy but when you’re ovulating, it is thin and clear.

This might sound vague, but once you know what to look for, it’s easy! And, if you aren’t sure, you can always use an ovulation test which will detect your LH levels through your pee.

As we said, this method relies on your judgement, so to help ensure accuracy, you might want to consider using a well-known app like Natural Cycles or check out Sensiplan Coach by Rebecca from Vrouw & Vruchtbaarheid.

Hopefully, this post has shed some light on the different birth control methods and which one is right for you. If you’re still confused, get in touch! We’re happy to help!