How Effective Is Birth Control Pill?

Duly Care
Jun 30
6 min read

The birth control pill is one of the most well-known ways for women to prevent an unintended pregnancy. It is easy to use and widely available. But there are some questions that many women think about: how effective is the birth control pill? Can you still get pregnant while using it?

These are common questions, and it is important to understand the answers clearly. In this blog, we will first explain what the birth control pill is, how it works, and then explore how effective it truly is.

Key Takeaways:

The birth control pill is a hormonal medication taken daily to prevent pregnancy. These contain synthetic versions of the natural female hormones estrogen and progesterone.
Birth control pills prevent pregnancy by preventing ovulation, thickening the cervical mucus and thinning the inner lining of the uterus.
The birth control pill can be highly effective, offering over 99% protection when taken exactly as directed. But with common mistakes like missed or late doses, its effectiveness drops to around 91%.
An unintended pregnancy can occur if the birth control pill is not used properly. Missing pills, taking them at irregular times, vomiting, or using certain medications at the same time can lower the pill’s effectiveness.

What is the Birth Control Pill?

Birth control pill, also known as oral contraceptive pill, are hormonal medications taken daily to prevent pregnancy. It contains synthetic versions of the natural female hormones estrogen and progesterone.

There are two main types of birth control pills - combined oral contraceptive pills (COCPs), which contain both estrogen and progestin (the synthetic form of progesterone), and progestin-only pills (POPs), which contain only progestin. COCPs are the most commonly used type of birth control pill, whereas POPs are usually recommended for women who cannot take estrogen due to medical reasons.

How Does The Birth Control Pill Work?

The primary benefit of birth control pills is preventing an unintended pregnancy. These pills do so by:

Stopping the release of an egg from the ovary each month (a process known as ovulation), which prevents fertilisation of the egg by sperm and the start of a possible pregnancy.
Thickening the cervical mucus, which makes it more difficult for the sperm to reach the egg.
Thinning the inner lining of the uterus, which prevents a fertilised egg from attaching, growing and developing into a pregnancy.

How Effective Is the Birth Control Pill at Preventing Pregnancy?

When taken correctly, the birth control pill is over 99% effective. This means that less than 1 in 100 women may get pregnant each year if they take the pill at the same time every day without missing any doses.

However, in real life, many women forget to take the pills or take them late. This causes the effectiveness of the birth control pill to drop to about 91%. This means that amongst women who take the pill incorrectly, around 9 in 100 women may get pregnant in a year while using the pill.

This difference between perfect and real life use shows how important it is to take the pill regularly and correctly. Missing pills or taking them late makes it more likely for the ovary to release an egg, or ovulation to occur, which increases the chance of a pregnancy.

If you start the combined oral contraceptive pill (COCP) within the first five days of your period, it works immediately. If you start it at any other time in your menstrual cycle, you need to use a backup method like condoms for the first seven days. For the progestin-only pill (POP), it takes 48 hours (two days) to start working, no matter when you begin taking it. During this time, it is important to use extra protection.

It should also be noted that, unlike barrier methods, the birth control pill is only effective at preventing pregnancy, not protecting against sexually transmitted infections.

Other Circumstances that Make the Birth Control Pill Less Effective

While the birth control pill is highly effective when used correctly, there are some situations where it may not work as well. These circumstances can lower the amount of hormones in your body, making it more likely for an egg to be released. If this happens, the risk of pregnancy increases. It is important to understand these situations so you can protect yourself better.

Vomiting or Diarrhoea: If you vomit (throw up) within two hours of taking the birth control pill, your body might not have had enough time to absorb the hormones. This means the pill may not work. The same can happen if you have severe diarrhoea (frequent, watery stools) for more than 24 hours. These stomach issues can prevent the hormones from entering your bloodstream properly.
If you vomit shortly after taking the pill, take another one as soon as you can. If your stomach issues continue, use a second form of contraception like condoms for at least seven days and speak to a doctor for advice.
Certain Medicines: Some medicines can lower the effectiveness of the birth control pill. These include some antibiotics like rifampin, medicines for epilepsy like phenytoin or carbamazepine, HIV medicines such as ritonavir, and herbal products especially St John's Wort.
These medicines can speed up how your liver breaks down the hormones in the pill. If that happens, there may not be enough hormones in your system to prevent ovulation. Always check with your doctor or pharmacist before starting any new medicine. They will let you know if you need to use a backup method.
Forgetting or Delaying a Dose: Taking the pill at different times each day or forgetting a dose altogether can lower its effectiveness. Hormone levels need to stay steady for the pill to work. If you miss a pill or take it many hours late, your body might release an egg, and you could get pregnant. Always follow the instructions in your pill pack or speak to a doctor if you're unsure what to do after a missed dose.

Can You Get Pregnant While Using the Pill?

It is possible to get pregnant while on the birth control pill, especially if it is not taken correctly. Here are some reasons why this might happen:

You missed one or more pills
You took the pill at different times each day
You vomited or had diarrhoea shortly after taking the pill which prevented its absorption in the body
You are taking certain medications that make the pill less effective. This includes some antibiotics and epilepsy drugs.

If the pill is not in your system at the right levels, your body may release an egg (ovulation may happen as normal), and you could become pregnant.

Conclusion

The birth control pill is a widely used and effective method of contraception when taken properly. But its success depends on how well and consistently it is used. Many factors, including missed doses, illness and other medicines, can lower its effectiveness.

If you are unsure about how effective the birth control pill is, or if you are considering starting or stopping it, speak to a doctor. Medical advice is essential when making informed decisions about the birth control pill. A doctor can help you understand your options and choose what is safest and most effective for you.

Frequently Asked Questions (FAQs)

How do I know if the pill is working for me?
If your periods become more regular and you do not experience unusual side effects, the pill is likely working well. Still, it is best to check with a doctor, especially in the first few months.
Can I rely only on the pill if I have sex often?
The pill can be over 99% effective if used correctly. Whether you have sex often or not is not the criterion to determine how effective it is at preventing pregnancy.
Does it matter what time of day I take the pill?
Yes. Taking the pill at the same time every day helps keep hormone levels steady. A doctor can guide you on the best routine based on the type of pill you are on. The time of the day that you choose for this does not matter as it is equally effective whether taken in the day or night, as long as it is taken at that same time every day.
What should I do if I vomit after taking the pill?
If you vomit within two hours of taking the pill, it might not be fully absorbed. Talk to a doctor or follow the instructions in your pill pack about what to do next.

Important

This blog, including its text, images, and infographics, is for educational purposes only and not a substitute for professional medical advice. For personalised advice, always consult a doctor.