Birth Control Pills: What You Need to Know


Over 10 million women in the U.S. currently use oral contraceptives, or “the pill,” to prevent pregnancy.[1,2] The pill is the most widely used method of birth control.

Many women not only use birth control pills for family planning methods, but also because the pill can alleviate some symptoms associated with their menstruation cycle or “period,” such as acne, anemia due to heavy menstrual bleeding, and premenstrual dysphoric disorder (PMDD).[3,4] PMDD is more than just premenstrual syndrome or PMS.  Women with PMDD suffer from particularly severe depression, tension, or irritability right before they have their period. Birth control pills can also be used to treat the often painful symptoms of endometriosis.

According to a report by the Guttmacher Institute, over 58% of women on oral contraceptives use them, in part, because of acne, anemia, or PMDD.  In August 2012, as part of the Affordable Care Act (Obamacare), birth control pills were made to be free of charge through all health insurance plans, except for plans provided by employers with religious exemptions.[5]

With dozens of FDA-approved birth control pills on the market, doctors and patients need to know how they work and are tested so that they can decide which pill is best to use.  Some provide the same steady dose of hormones throughout the month. Others vary the type of hormone and only cause you to have your period a few times a year.  Certain pills also use different types of hormones at various dosages.  Newer formes of oral contraceptive pills are introduced every few years, with some sparking controversy over potentially harmful side effects.  Understanding how birth control pills work and how the FDA determines whether they are safe and effective can help demystify the process of choosing the birth control pill that is right for you.

How Birth Control Pills Workbirth control pills facts, yaz

During the menstrual cycle, two hormones, follicle-stimulating hormone (FSH) and estrogen increase, allowing a mature egg to develop in the ovaries.  Next, ovulation occurs when another hormone, luteinizing hormone (LH), spikes and causes the release of the hormone progesterone.[6] Progesterone is important because it allows the lining of the uterus to thicken, creating a desirable environment for a fertilized egg to attach itself.

Birth control pills contain synthetic forms of estrogen and progesterone.  These synthetic hormones help keep the natural levels of estrogen and progesterone in your body constant so that eggs do not mature and the lining of the uterus never develops enough for a fertilized egg to implant.  Regulating these hormones in this way also thickens the cervical mucus, making it more difficult for sperm to reach an egg.

If a woman takes contraceptive pills every day, she will never have a period.  However, most monthly packs of birth control pills include a week of pills that do not contain any hormones. These “placebo” or sugar pills reinforce the habit of taking a pill every day so that women will not forget to take the pills with hormones that actually prevent pregnancy.  Women usually expel the lining in their uterus, which results in bleeding similar to a “period” during the four to seven days they take the placebo pills.

The bleeding you have while taking oral contraceptives is not a real period, because the lining of the uterus does not fully thicken and an egg has not been released.  In other words, birth control pills don’t really “regulate your period,” they just make it seem as though your period is regular.  This is why Seasonale and other birth control pills can safely schedule “periods” only four times a year.  With these pills, you are simply choosing quarterly artificial periods instead of monthly ones.  That’s why some women don’t have normal periods for several months after they stop taking birth control pills.  It can take time for the body’s natural hormonal response to readjust. However, this does not affect a woman’s ability to become pregnant.

Emergency Contraception

Emergency contraceptives (the “morning-after pill”) are used after intercourse has already taken place. They prevent pregnancy by delaying the release of an egg from the ovaries and, possibly, by thickening cervical mucus and making “swimming conditions” for sperm unfavorable.[7,8,9] Studies indicate that emergency contraception does not prevent implantation; it simply keeps the egg and sperm from ever meeting. When women took emergency contraception before they had ovulated, they became pregnant at a much lower rate. When women took emergency contraception after ovulation, they became pregnant at a rate comparable to women who had not taken emergency contraception. If emergency contraception prevented implantation, the women who took it after ovulating would have gotten pregnant at lower rates than women not taking emergency contraception. Plan B and ella are the two most common emergency contraceptives. Plan B can be taken up to 72 hours following intercourse and ella may be taken within 120 hours. Estimated effectiveness in preventing pregnancy ranges from 52% to 94%. Reported side effects include nausea, vomiting, headache, breast tenderness, cramps and fatigue.[10] For more information on emergency contraception visit our article on Morning After Pills.

How has the Pill Changed Over the Years?

Oral contraceptives used to contain high amounts of the hormone estrogen, but now many birth control pills contain a very low dose mix of a synthetic form of estrogen and a synthetic form of progesterone known as progestin.  Manufacturers have lowered the doses and introduced new types of progestin over the years in an effort to decrease side effects such as blood clots.

Birth control pills that contain a mix of estrogen and some form of progestin are known as combined oral contraceptives.  Combined oral contraceptives vary in terms of the types and amounts of estrogen and progestin.  Besides combined oral contraceptives, there are also progestin only pills called the “mini pill,” which is typically prescribed for women who are breastfeeding or cannot take synthetic estrogen.

Generally, older forms of progestins  (called 1st and 2nd generation progestins) tend to decrease unwanted side effects such as increased blood sugar levels, but the newer forms (called 3rdand 4th generation progestins) increase the risk of blood clots compared to their predecessors. [11]

Generations of Progestins

First Generation

Second Generation

Third Generation

Fourth Generation

Norethisterone (NET) Norethindrone (NE)Ethynodiol diacetateLynestrenol (LYN) Levonorgestrel (LNG) Norgestrel (NG) Desogestrel (DSG)Gestodene (GSD)Norgestimate (NGM) Drospirenone (DRSP)

The Risks of Pregnancy and Birth Control

While there are some risks to taking birth control pills, especially if you are over the age of 35, are a smoker, have a history of blood clots or breast cancer, and/or are currently breastfeeding, using combined oral contraceptives are safer than pregnancy.[12] While pregnancy is generally safe for healthy young women with good access to prenatal care, there are health risks.  One major study found that the percentage of deaths among women ever using oral contraceptives was 12% lower than those that never did.[13,14] Women on birth control pills have an elevated risk of blood clots, but that risk is lower than the risk of developing blood clots during pregnancy and the six weeks after delivering a child (postpartum).  Also, women who use oral contraceptives have a lower risk of ovarian, endometrial, and colorectal cancers.

Taking birth control pills increases the risk of blood clots compared to not taking them, but because they are so effective at preventing pregnancy, the FDA has approved birth control pills as safer than being pregnant.  Again, this FDA approval does not mean tht birth control pills are entirely safe–just safer than the alternative, which is pregnancy.

Research indicates that there are additional risks in taking birth control pills for women over 40.  A 2013 study found that women over age 40 who had used birth control pills for at least 3 years had an increased risk of developing glaucoma, a degenerative eye disease that may eventually cause blindness.[15] Their risk of developing this condition was twice as high as the risk for similar women of the same age who had not taken birth control pills for at least 3 years. Researchers think that this risk may be due to a decrease in estrogen when women take birth control pulls, a hormone that contributes toward protecting our eyes. Since all women over 40 are at greater risk of heart disease than younger women, and because birth control pills have cardiac risks as noted earlier, women over 40 might want to consider other equally effective types of contraceptives.  Those who stay on birth control pills should consider a yearly eye screening to check for glaucoma as well as annual check-ups to evaluate their heart health.

Does Newer Mean Better or Safer?

New birth control pills are introduced to the market all of the time, but newer does not always mean better. For instance, the synthetic progestin levonorgestrel, which has been on the market for decades, is safer than several newer synthetic progestins, such as drospirenone.  The latest research on drospirenone, which is in Yaz, Yasmin, and Beyaz (all made by Bayer, as well as Gianvi, Loryna, Ocella, Safyral, Syeda, and Zarah (the generic forms of Yasmin and Yaz), shows that these pills are significantly more likely to cause potentially fatal blood clots.[16] Several studies show them to have twice the risk of other combined hormonal contraceptives.

To find out more about the risks of drospirenone (also called DRSP), read Are Bayer’s Birth Control Pills Too Risky? You can learn about one young woman’s tragic experience on  Why not save yourself some money and reduce your risk of blood clots, which can travel in the body and become fatal, by choosing a birth control pill with a synthetic hormone that has been on the market for a longer time and proven to be safer?

Do Birth Control Pills Have Other Benefits?

It is important to keep risks such as blood clots in mind if you are considering to use birth control pills to “regulate your period” or for reasons other than preventing pregnancy.  Is the risk of potentially fatal blood clots worth it to reduce cramping, or might Tylenol or other pain killers be equally effective without the increased risks?  Since birth control pills don’t actually regulate a woman’s period, they should never be used for that purpose.  If the goal is to reduce menstrual bleeding, then birth control pills can accomplish that, but with risks that may outweigh the benefits.

While all FDA-approved oral contraceptives are proven to prevent pregnancy, some have also been approved for other benefits.[17] However, the benefits of birth control pills approved for PMDD—(like Yaz and Beyaz)—have mostly been evaluated by comparing them to placebos and not to other birth control pills. They may not be any more effective than safer, less expensive birth control pills for PMDD.  So, why didn’t the FDA approve these other pills for PMDD?  The answer is simple: money.  Yaz and other relatively new birth control pills are very expensive, which is why the company selling them was willing to spend the extra money to apply for FDA approval for PMDD.  Older birth control pills that are widely available in generic forms cost much less, so their companies have no incentive to pay the millions of dollars it would cost to apply for FDA approval specifically treat PMDD.

The FDA has also approved Yaz, Ortho Tri-Cyclen, and Estrostep Fe for reducing acne for women who use the pill for contraception. It is important to note that the FDA has not approved these drugs for acne unless the women also need a contraceptive; otherwise, the risks of these drugs would outweigh the benefits. It is unknown if any of those contraceptive pills are better at reducing acne than other birth control pills, whose companies did not apply for FDA approval for acne.  As a side note, birth control pills are less effective at reducing acne than some other types of acne medication.

It is important to remember that everyone’s body is different, and pills can have risks or benefits for your friends or relatives that are different from the ones you will experience.  If a particular type of birth control pill is causing problems for you, talk with your healthcare provider about making a change.  If you are on a birth control pill that has been shown to have higher risks of blood clots and other complications, why not switch to a safer, less expensive pill?

To read more about the dangers of birth control pills containing drospirenone, click here.

Related Articles and Resources

Letters to Annie: Be Your Own Reproductive Health Advocate
Are some birth control pills too risky?

Emergency contraception (morning-after pills)
Essure permanent contraception device: not so permanent and many side effects

  1.  Mosher WD, Jones J. Use of contraception in the United States: 1982-2008. National Center for Health Statistics. Vital Health Stat 23(29). 2010.
  2. Guttmacher Institute. In brief: facts on contraceptive use in the United States. (2010) Retrieved from:
  3. Jones RK, Beyond Birth Control: The Overlooked Benefits of Oral Contraceptive Pills, New York: Guttmacher Institute, 2011.
  4. U.S. Department of Health and Human Services.  Affordable care act ensures women receive preventive services at no additional cost, 2011. Retrieved from:
  5. United Healthcare. Religious Exemptions to Contraceptive Coverage, 2014. Retrieved from: 
  6. Vankrieken, L., & Reuben, H. (1999). Hormonal levels during the early follicular phase of the menstrual cycle. Diagnostic Products Corporation, Retrieved from 
  7. Trussell, James and Kelly Cleland. (2012). Emergency contraception: How it works (how it doesn’t). Science Friday. Retrieved from
  8.  Lloyd, S. (2012). Controversy surrounding emergency contraception. EmpowHER. Retrieved from,0
  9. Clinical proceedings. (2011). Update on Emergency Contraception. In Association of Reproductive Health Professionals (Ed.).
  10. Office of Women’s Health. (2012). Birth Control Guide. In U. S. Food and Drug Administration (Ed.).
  11. Lidegaard Ø, Nielsen L, Skovlund C, Skjeldestad F, Løkkegaard E. 2011. Risk of venous thromboembolism from use of oral contraceptives containing different progestogens and oestrogen doses: Danish cohort study. BMJ; 343: d6423 doi: 10.1136/bmj.d6423
  12. Hannaford P, Iversen L, Macfarlane TV, Elliot AM, Angus V, Lee AJ (2010). Mortality among contraceptive pill users: cohort evidence from Royal College of General Practitioners’ Oral Contraceptive Study. British Medical Journal 2010; 340:c927
  13. Shulman, L. (2011). The state of hormonal contraception today: benefits and risks of hormonal contraceptives. American Journal of Obstetrics & Gynecology205(4), doi: 10.1016/j.ajog.2011.06.057
  14. Maguire, K., & Westhoff, C. (2011). The state of hormonal contraception today: established and emerging noncontraceptive health benefits. American Journal of Obstetrics & Gynecology205(4), doi: 10.1016/j.ajog.2011.06.056.
  15. Wang YE, Tebaldi de Queiroz B, Wang SY, & Lin SC. Association between oral contraceptive use and glaucoma in the United States. Poster presented at the 2013 American Academy of Ophthalmology. Accessed November 22, 2013.
  16. FDA Office of Surveillance and Epidemiology. 2011. Combined hormonal contraceptives (CHCs) and the risk of cardiovascular disease endpoints
  17. Arowojolu AO, Gallo MF, Lopez LM, Grimes DA, Garner SE. Combined oral contraceptive pills for treatment of acne. Cochrane Database of Systematic Reviews 2009, Issue 3. Art. No.: CD004425. DOI: 10.1002/14651858.CD004425.pub4