How Birth Control Works & How It Affects Your Cycle
Female Body

How Birth Control Works & How It Affects Your Cycle

Jasmine Chiam Jasmine Chiam

Birth control, also known as contraception, prevents you from getting pregnant with sexual intercourse. 

Most women will utilize birth control at some point in their life. And in 2019, over 900 million women across the globe were estimated to be using some form of contraception [1]. That's a phenomenal number. 

But despite its widespread use, it's pretty common to have some questions about the different methods of birth control. 

Some questions women usually have about contraception go along the lines of this—How does birth control work, and is it effective? How does birth control change your cycle?

You may be wondering the same as well. So, we're here to walk you through some of the doubts and questions you may have. 

In this article, we'll explore the various types of contraceptive methods, how they work, their side effects, and how these different contraceptive methods may affect your cycle. 

Without further ado, let's dive into it!

Types Of Birth Control 

Birth control can be split into two categories—hormonal and non-hormonal birth control. Some methods of birth control are permanent, while others aren't. 

With the massive number of options you have, it can be really challenging to pinpoint the many differences between each type. But let's break it down slowly. 

Hormonal Birth Control 

Frequency/How To Use [2]. 

Birth control pills 

These pills are taken daily. Usually, you'll take a pill every day for 21 days, and this is followed by a 7-day break. During this break, you'll either stop taking the pills or take placebo pills that contain no hormones.

Vaginal rings 

Keep it in for three weeks, leave it out for a week, and then put in a new ring. 

Hormonal injection 

The shot is given once every three months. 

Birth control implant 

An implant can last for at least three years. 

Hormonal IUD

The hormonal IUD lasts between 3-6 years. The IUD is a T-shaped device placed into the uterus. 

Birth control patches 

One patch lasts for one week. Use three patches for three weeks, and on the fourth week, don't apply a new patch. 

Non-hormonal Birth Control

Frequency & Schedule of Use 


The male partner will use a new condom each time they have sex. 

Cervical cap or diaphragm 

The female partner inserts a cervical cap into the vagina (covering the cervix) before sex. 


The female partner inserts the sponge containing spermicide into the vagina before sex. 


The female partner places spermicide deep into the vagina before sex. 

Copper IUD 

Depending on the brand, copper IUDs can last anywhere between 4-12 years [3].


This method is meant to be permanent, and reversal can be complicated. 

One factor to take into mind when choosing a suitable contraceptive method for yourself is its duration of effect. 

Say you have no issues with using a contraceptive method that requires you to remember to take or use it regularly. In that case, something like birth control pills or patches will be suitable. 

However, if you find this challenging to remember, a set-and-forget method may be more suitable. Contraceptive methods like the IUD or implant work for years once they've been inserted. 

Natural Birth Control 

Natural birth control is another method of contraception that relies on making observations of your body and menstrual cycle. You won't be using any hormones, medications, or devices. 

For instance, the calendar rhythm method is a fertility awareness-based method (FAM) that involves tracking your menstrual cycle to predict when you'll ovulate and be fertile. You will then avoid having sex during your fertile period. 

The basal body temperature (BBT) method is often used alongside the calendar rhythm method. To do this, you'll take your temperature in the morning when you wake up. Sexual intercourse should then be avoided from the start of menstruation until approximately three days after the spike of BBT. However, research has shown that this can be highly unreliable [4]. 

Your gynaecologist or doctor will be able to guide you through the various natural methods of birth control if it is something you're keen on. 

How Does Birth Control Work? 

Before we can grasp how birth control works its magic, let's quickly explore how a fetus is formed

For that to happen, a viable sperm must meet a mature egg that will be released from the ovary in a process called ovulation. When the two meet and fuse, fertilisation takes place. The fertilised egg must then attach itself to the walls of the uterus (implantation). 

Take any piece of the puzzle away, and fertilisation cannot successfully occur. This means you could do any of the following [5]:

  • Stop the little swimmers from meeting the egg.
  • Prevent an egg from fully developing or being released by the ovary (preventing ovulation). 
  • Prevent implantation of a fertilised egg from taking place. 

And that's how contraception works behind closed doors. 

Non-hormonal Birth Control 

Some types of non-hormonal birth control, like condoms and diaphragms, form a barrier between the sperm and the egg and prevent these swimmers from reaching the grand prize. Other methods, like spermicide, will hamper the movement of the sperm or kill them off altogether [6]. 

The effectiveness of these methods in real life (taking into account errors of use) isn't the highest. The efficacy rate is around 79-95%, or about 5 to 21 pregnancies per 100 women each year, depending on the exact method used [7, 8]. These rates pale in comparison to the copper IUD. 

The copper IUD has spermicidal effects, as copper is toxic to sperm. It also hinders the normal movement of sperm and causes changes in the uterus to make it less favourable for implantation. [5, 6] 

The copper IUD is highly effective and is estimated to account for only one pregnancy per 100 women each year. That's a much greater efficacy compared to the other non-hormonal methods [7, 8]. 

Hormonal Birth Control 

Alright, let's move on to the hormonal forms of birth control. 

It's time to get acquainted with two very important hormones: Progestin and estrogen. 

If you're wondering, progestin is the man-made version of a hormone that your body naturally produces called progesterone. 

But what do progestin and estrogen do to prevent pregnancy? 

Progestin works via the following mechanisms [5, 6]: 

  • Suppresses the release of gonadotropin-releasing hormone and luteinizing hormone, and this prevents ovulation from happening in some women (other women may still continue ovulating) 
  • Thickens the cervical mucus, making it harder for sperm to swim through it
  • Changes the uterus lining to become less suitable for implantation 

Estrogen is typically used in combination with progestin in some contraceptives. Its mechanism of action overlaps with progestin in some ways. 

Estrogen does the following [5, 6]:

  • Suppresses the release of follicle-stimulating hormone and luteinizing hormone, preventing ovulation
  • Prevents implantation and the attachment of a fertilised egg to the uterine wall
  • Reduces irregular bleeding while you're on hormonal birth control. 

Contraceptives may contain just progestin alone or a combination of both estrogen and progestin.  

For instance, some birth control pills contain just progestin, while others contain both hormones. The pills containing both hormones are called combined oral contraceptive pills (COCP). 

In general, birth control pills have a lower failure rate than condoms and other barrier methods. However, all IUDs and birth control implants have a lower failure rate than contraceptive pills. 

About (or less than) 1 in 100 women will get pregnant each year using an implant or IUD [7]. That's a pretty decent efficacy rate! 

Do I Get My Period On Birth Control? 

One question you may have is this—Does birth control stop your period? 

Well, yes, hormonal birth control can stop your periods, simply because they prevent ovulation from occurring. That might be a little hard to wrap your head around. But let's break it down bit by bit. 

You may have picked up a pack of COCPs at the pharmacy before and noticed the pills came in two different colours. Perhaps, most of them were white, and a smaller group of them came in pink. These pink placebo pills do not contain any hormones

The common misconception here is this: While you're on those special pink pills, you can expect your 'period' to happen during that week. 

Yes, you will notice bleeding during that time frame, and yes, you'll still need your trusty friends—the pad and tampon. But this isn't your "real period." It's more accurately termed withdrawal bleeding (more on this further below). 

In essence, it really only makes sense to speak of a menstrual period when ovulation is occurring as well. 

This is because a menstrual period refers to the shedding of the uterine lining, which occurs due to the drop in hormones when the released egg is not fertilised. In the medical world, a menstrual period technically cannot happen if the release of a mature egg does not occur (ovulation). 

Ovulation is typically prevented by hormonal methods of birth control, like the COCP, vaginal ring, birth control patches, injection, implant, and often, the hormonal IUD as well [2]. 

However, do note that many women will still continue having their periods on lower-dose hormonal IUDs, which is less likely to impact ovulation [9].

But since no ovulation occurs with most hormonal birth control methods, you cannot get a "real period." Nonetheless, this doesn't mean you won't bleed at all (we'll explore this in the next section). 

So what happens when you get off hormonal birth control, then? Do your periods come back? 

When you do stop your hormonal birth control, ovulation is no longer prevented. But it is normal to get late or irregular periods. In fact, it may take months for your periods to go back to normal. Your fertility will also return, but how quickly it does depends on the method of birth control used [2]. 

What Is Withdrawal Bleeding? 

Withdrawal bleeding happens due to the drop in hormones when your body no longer receives an external source of hormones. 

For instance, this happens during the scheduled breaks while you're taking the placebo pills that don't contain hormones. As a result, the lining of the uterus begins to shed. This is usually lighter than your normal menses. 

And there you have it—something that mimics your period but isn't your period. 

Your uterus doesn't shed its lining as it would during your normal period and cycle. And in fact, your natural cycle is 'overwritten' by the introduction of these hormones into your body. This artificial cycle replaces it instead [10].

Which birth control methods lead to withdrawal bleeding? 

Other than COCPs, the vaginal ring and birth control patch also lead to this withdrawal bleed. 

The birth control implant, injection, and hormonal IUD typically do not cause withdrawal bleeding—that is until you stop these hormonal birth control methods. 

You may still experience some bleeding while on these methods of birth control, but this isn't considered withdrawal bleeding. These methods of birth control supply a steady stream of hormones to your body, so there isn't any break in the cycle for a drop of hormones to occur [2]. 

And how about non-hormonal birth control? 

Well, non-hormonal methods of birth control do not cause withdrawal bleeding. For instance, you'll still cycle through your "real menses" for something like the copper IUD. However, for the copper IUD, your periods may become irregular or heavier [9].

How Birth Control Affects Your Cycle 

Hormonal birth control and the copper IUD can affect your bleeding pattern. You may notice heavier or lighter periods, irregular bleeding, or spotting. You may notice your bleeding stops altogether with certain methods of contraception. 

The effects of contraception vary from one woman to another. But in general, here's how the different birth control types can affect your cycle and bleeding patterns. 

Birth Control Type 

Possible Changes in Bleeding Patterns 

COCP (pills containing both estrogen and progestin), birth control patch, & vaginal ring 

You may experience spotting or irregular bleeding in the first few months of use, but this usually improves. 

If you're on a continuous regimen, you'll likely stop having periods altogether after the first few months of use [9]. 

Progestin-only pills 

Spotting and bleeding irregularities are very common, and around 10% of women stop bleeding altogether [9]. Around 50% of women will still experience monthly bleeding on these pills [9]. 

Birth control injection 

Irregular bleeding and spotting are common in the first 3 months. But many women will stop having their periods altogether with prolonged use [9]. 

Birth control implant 

Spotting and irregular bleeding are very common in the first 3 months. However, they typically do not disappear over time. And you'll likely experience these bleeding irregularities over the 3-year duration of use [9]. 


Irregular bleeding, cramping, and spotting are common in the first 3-6 months of use. This usually gets better over time. 

The copper IUD may cause your periods to become heavier. On the flip side, the hormonal IUD may cause your menses to become lighter or stop them completely [9]. 

Bleeding irregularities and spotting can be common with hormonal birth control. And understandably, this can be distressing. 

If you have worries or questions, it's always best to address them with your healthcare professional.

Other Benefits Of Hormonal Birth Control 

Birth control isn't the only thing you can use birth control for. 

Here are some other non-contraceptive benefits of birth control, namely the combined oral contraceptive pill: 

  • Improving menstrual disorders such as painful periods [11]
  • Regulating your periods [12] 
  • Reducing heavy bleeding [11]
  • Managing acne or excessive hair growth in women [12] 
  • Reducing your risk of endometrial or ovarian cancer [12] 
  • Managing polycystic ovarian syndrome (PCOS) [14] 

You should, of course, seek the advice of your health provider before starting hormonal birth control for any of these other reasons. 

Side Effects Of Birth Control

You may be concerned about how hormonal birth control may affect your body in the long run. And birth control could indeed lead to various side effects, depending on the method you opt for. 

Based on research, these are some of the possible side effects of hormonal birth control: 

  • Side effects of COCPs include migraines, nausea, breast tenderness, or pelvic pain [6].  
  • Birth control methods containing both progestin and estrogen, such as the COCP, may increase your risk of stroke, breast cancer, or deep vein thrombosis (a blood clot in one of your deep veins) [6]. 
  • Irregular bleeding is a common side effect of the birth control injection and implant [6]. 
  • Hormonal contraception may affect mood and increase depressive symptoms, irritability, or anxiety, but further research is needed to confirm this [13]. 

Nonetheless, some of these side effects, such as spotting or irregular bleeding, may improve over time. Other more serious side effects are much rarer. But your lifestyle or medical conditions may also affect how likely you are to experience these side effects. 

Hence, it's always best to let your healthcare provider know about your general lifestyle habits, current medications, and medical conditions. That way, they can suggest a method that's safest for you. You can also ask your healthcare professional to inform you of the side effects requiring prompt medical attention so you can keep an eye out for them. 

Birth control is safe for many women, and serious complications are rare. But any concerns you have are completely understandable. So you may wish to find a safe space to discuss them with a health professional. 

Final Takeaway: Birth Control And Your Cycle 

It's understandably difficult to decide which birth control method suits you best. But we hope that the above information has made the process easier to navigate for you. As always, your healthcare professional will be able to provide advice on choosing the best method of contraception for yourself. 

If you're getting off birth control and looking to get pregnant, it can be hard to track your cycle and pinpoint your fertile period. 

Hormonal birth control can change your cycle significantly, and it may take months for your menses to return to normal once you stop. But we've got something that can help you track your cycle more effectively during this period. 

The inne minilab is an at-home, hormone-tracking device that allows you to track and learn more about your cycle through simple saliva tests. The minilab allows you to see your unique hormonal curve, predict when your ovulation and period are likely to happen, and pinpoint your fertile period. 

Tracking your cycle has never been easier! 


1. Contraceptive Use by Method 2019. United Nations, Department of Economic and Social Affairs. Updated Jan 2019. Accessed 18 July 2022.

2. Kaunitz, AM. Patient education: Hormonal methods of birth control (Beyond the Basics). UpToDate. Waltham, MA: UpToDate Inc. Updated 29 Jan 2021. Accessed 18 July 2022

3. Wu JP, Pickle S. Extended use of the intrauterine device: a literature review and recommendations for clinical practice. Contraception. 2014;89(6):495-503. doi:10.1016/j.contraception.2014.02.011

4. Steward K, Raja A. Physiology, Ovulation And Basal Body Temperature. In: StatPearls. Treasure Island (FL): StatPearls Publishing; July 22, 2021.

5. Hatcher RA, Kowal D. Birth Control. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 174. Available from: 

6. Teal S, Edelman A. Contraception Selection, Effectiveness, and Adverse Effects: A Review. JAMA. 2021;326(24):2507-2518. doi:10.1001/jama.2021.21392 

7. Trussell J. Contraceptive failure in the United States. Contraception. 2011;83(5):397-404. doi:10.1016/j.contraception.2011.01.021

8. Polis CB, Bradley SE, Bankole A, Onda T, Croft T, Singh S. Typical-use contraceptive failure rates in 43 countries with Demographic and Health Survey data: summary of a detailed report. Contraception. 2016;94(1):11-17. doi:10.1016/j.contraception.2016.03.011

9. Villavicencio J, Allen RH. Unscheduled bleeding and contraceptive choice: increasing satisfaction and continuation rates. Open Access J Contracept. 2016;7:43-52. Published 2016 Mar 31. doi:10.2147/OAJC.S85565

10. Stubblefield PG. Menstrual impact of contraception. Am J Obstet Gynecol. 1994;170(5 Pt 2):1513-1522. doi:10.1016/s0002-9378(94)05013-1

11. Hogue CJ, Hall KS, Kottke M. Hormonal Contraceptives Improve Women's Health and Should Continue to Be Covered by Health Insurance Plans. Ann Intern Med. 2017;167(9):666-667. doi:10.7326/M17-2011

12. Costa FJ. Beneficios nao contraceptivos da contracepcao [Non-contraceptive benefits of contraception]. Sex Planeam Fam. 1995;8(2):16-18.

13. Lewis CA, Kimmig AS, Zsido RG, Jank A, Derntl B, Sacher J. Effects of Hormonal Contraceptives on Mood: A Focus on Emotion Recognition and Reactivity, Reward Processing, and Stress Response. Curr Psychiatry Rep. 2019;21(11):115. Published 2019 Nov 7. doi:10.1007/s11920-019-1095-z

14. Shah D, Patil M; National PCOS Working Group. Consensus Statement on the Use of Oral Contraceptive Pills in Polycystic Ovarian Syndrome Women in India. J Hum Reprod Sci. 2018;11(2):96-118. doi:10.4103/jhrs.JHRS_72_18

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