Hormonal contraceptives: What different types are there, and how do they work

Did you know that more than 40% of women use some form of contraception worldwide? ¹

When it comes to choosing the best contraceptive method for you, there are many things to consider, the first one being: hormonal or non-hormonal birth control? In this article, we will talk about the different types of hormonal birth control, and how they work.

What is hormonal birth control?

Hormonal contraceptives are based on the use of estrogens and progestins, which are the main hormones involved in controlling the menstrual cycle. Most are reversible methods, meaning that once they are no longer used, the possibility of becoming pregnant returns to what it used to be. They are highly effective in preventing pregnancy when used correctly but have no effect against sexually transmitted diseases (STIs).

What does hormonal birth control do?

To better understand how hormonal contraceptives work, let us give you a very simplified explanation of the female menstrual cycle:

The main female sex hormones are estrogen and progesterone. Both are responsible for regulating the different stages of menstrual cycle and for changes in the endometrium (the inner lining of the uterus). Throughout the female menstrual cycle, the amounts of estrogen and progesterone vary, first causing the endometrium to break down and shed (this is what menstrual bleeding is), and then making it thicken again. Estrogen and progesterone are also involved in the process of ovulation, where an egg is released by the ovaries.

Hormonal contraceptive work by mimicking these natural female sex hormones and interfering in the menstrual cycle. They thicken the cervical mucus, which stops sperm from reaching the uterus, or they prevent ovulation from happening. Both methods of action prevent pregnancy by not allowing the egg to be fertilized in the first place.

Although it is not their main purpose, hormonal contraceptives can have non-contraceptive benefits, and can sometimes be prescribed by health care providers to treat certain medical conditions, such as excessive menstrual bleeding (menorrhagia), painful periods (dysmenorrhea), acne, excessive hair growth (hirsutism), polycystic ovarian syndrome (PCOS), and endometriosis. ² How the different methods can be used will depend mainly on the active ingredients, whether they contain both estrogen and progestins, or only progestins, and their dose.

Combinations in hormonal contraceptives:

For hormonal contraceptives to be effective in preventing pregnancy, they must contain a progestin, which is what inhibits ovulation. Therefore, hormonal contraceptives can contain progestins by themselves or in combination with estrogens. When both estrogens and progestins are present, these are called combined hormonal contraceptives.

So, which one is better, progestin-only or combined hormonal contraceptives? They cannot be classified into “better” or “worse”, they are just different, and their benefits and risks are different depending on the person taking them.

Combined hormonal contraceptives are not recommended for all women. For example, because estrogens have been linked to in increased risk of blood clots, it is not recommended that women over a certain age, or with other risk factors use combined hormonal contraceptives. For women who cannot take combined hormonal contraceptives, progestin-only contraceptives are a potential alternative. However, with some progestin-only contraceptives, it is common for unexpected bleeding or spotting to occur between regular bleeds.

Types of hormonal birth control

Oral birth control

Daily method, commonly known as “the pill”, which usually regulates the menstrual cycle into 28-day cycles. These are usually taken once a day for either 21 or 24 days, followed by 7 or 4 days of placebo (inactive) pills or “rest days”, depending on the drug, before starting the next cycle. During these rest days is when withdrawal bleeding can occur (vaginal bleeding similar to menstruation). Some birth control pills are given on a continuous regimen, where there are no rest days or placebo pills, and all 28 pills are active pills. Oral birth control can be divided into two main types:

Combined oral contraceptives (COCs) contain both estrogen and progestin to prevent ovulation from occurring. Most traditional pills are combined ones and differ from each other by the amount and type of estrogens and progestins included in each formula.
Progestin-only pills (POP): these are estrogen-free alternatives. Progestin is the key hormone in contraceptives, as it prevents ovulation, changes the cervical mucus and the lining of the uterus.

When POPs or COCs are used correctly, only about 0.3% of women become pregnant during the first year of taking them.

Vaginal rings

Small, flexible ring that is placed by the user in the vagina. In terms of effect duration and how often the ring should be replaced, there are two main types: monthly and yearly rings.

Vaginal rings contain the same hormones as oral contraceptives, but in this case, they are released continuously and at a lower dose in the vagina, where they are absorbed.

The ring can be removed for up to 3 hours without the need to use backup contraception. After this time, additional contraception should be used for 7 days after re-inserting it. This method has a similar pregnancy rate than oral contraceptives and is easier for some people to use correctly because they don’t need to remember to take a daily dose.

Transdermal skin patch

Weekly method, where a skin patch is placed on the skin, and stays in place sticking to the skin with an adhesive. The patch is then replaced every 7 days for 3 weeks, followed by one rest week with no patch. It also has a similar pregnancy rate as oral contraceptives when used correctly and doesn’t require remembering to take a pill every day. However, if the patch is not replaced in time, or more than 2 days go by without using the patch, backup contraceptive methods should be used for 7 days after placing a new patch. One downside of the patch is that it is less effective in women with a body mass index (BMI) of 30 or more.

Hormonal contraceptive implant

A long-acting progestin-only method of contraception. The contraceptive implant is a flexible plastic rod, which is placed under the skin in the upper arm. The implant releases a low, regular dose of the hormone progestin. It lasts from 3 to 5 years, and it must then be changed by a specialist. This implant can be removed at any time you wish to become pregnant.

Hormonal intra-uterine device (IUD)

There are two types of IUDs, the non-hormonal, and the hormonal IUD. They require an invasive procedure to be able to place it correctly. It is a flexible piece of plastic that is placed inside the uterus and can be used for several years but can be removed at any time by a medical professional. Once it is inserted, the hormonal IUD acts as a reserve of progestin, and a small amount is continuously released into your body. They are very effective, and only around 1% of women become pregnant throughout the many years of use. It is believed that it is so effective because the correct use of this method doesn’t depend on the user.

Contraceptive injections

This involves the injection of a specific progestin every 3 months. The injections must be carried out by a health care practitioner, and is very effective when used correctly, where only 0.2% of women become pregnant during the first year of using it. It is common for this type of birth control to result in absence of menstrual bleeding and can decrease bone mineral density (BMD) while it is being used, which normally returns to what it was previously after the injections are stopped. ³ This is the only reversible hormonal contraceptive method that takes time to be fully reversed. Once injections are started, it can take up to 18 months for fertility to go back to what it was before.

So, what is the best option?

Now that we know what hormonal birth control options there are, and how they work, you might be thinking to yourself: What is the best hormonal birth control?

There is no answer to that question. All hormonal birth control is effective when used correctly, they all have their pros and cons, meaning that the best method is different for each person. It is important to consult with your gynecologist or healthcare professional about what options are available to you, so they can recommend and guide you based on your specific needs and preferences.

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