Emergency contraception (morning-after pills)

Diana Zuckerman, PhD, Dana Casciotti, PhD, Jennifer Shapiro,

and Morgan Wharton

National Center for Health Research

Our nation’s public debate over abortion has prevented many girls and women who have had unprotected sex, including victims of rape, from gaining the information they need to prevent an unwanted pregnancy. Each year in the United States, about one-half of the 6-million pregnancies are unintended.  And more than half of all those unintended pregnancies occur when women experience contraceptive failure.1

Emergency contraceptives, commonly known as “morning-after pills,” are medical products that prevent pregnancy after intercourse or birth control failure. They are not abortion pills because they prevent pregnancy by delaying the woman’s ovulation and, possibly, by thickening cervical mucus and keeping the sperm from reaching the egg.2 3 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 ovulating, they became pregnant at a much lower rate. When women took emergency contraception after ovulating, they became pregnant at a rate comparable to women whohad 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.4 2 These pills will not work if a woman is already pregnant and they will not cause an abortion.

Emergency contraception is not yet widely understood in the U.S., which may be a result of limited direct advertising to patients and barriers to access.  Consequently, many women do not know that emergency contraceptive pills (ECPs) are effective, safe, and readily available in pharmacies.

Even the widely recognized name, the “morning-after pill,” is not exactly accurate.  Emergency contraceptives can be taken sooner than the morning after unprotected sex or contraceptive failure, and some versions require more than just one pill.  Some ECPs are more effective when taken immediately after intercourse, and others can effectively prevent pregnancy 3-5 days after intercourse.5

Although emergency contraception has been available for several decades, many girls and women never knew it existed, and it is only recently that products have been sold specifically for that purpose.  Before the current products were on the market, women were using other “morning-after” strategies to prevent pregnancy, such as using a higher than usual dose of birth control pills (2-5 pills, depending on the type) or having a copper wire intrauterine device (IUD) inserted within 5 days of  intercourse.  The copper T IUD is still an approved method of emergency contraception-it can be inserted up to 5 days after unprotected sex-but it requires a medical provider to insert the small device into the uterus.5


Birth control pills have been used as emergency contraceptives since the mid-1960’s, but this “off-label” use was not approved by the U.S. Food and Drug Administration (FDA) until 1997.6 In 1998, a new emergency contraceptive was introduced and sold under the name Preven.  Like birth control pills, Preven contained progestin and estrogen, and if taken within 3 days (72 hours) of intercourse could prevent a woman from getting pregnant.

Preven was discontinued in 2004 because progestin-only pills were found to be more effective and caused fewer adverse effects than the combined pill.  The products currently on the market are slightly different.

Emergency Contraception Pills (ECPs) Now

The 2 most common types used in the U.S. are:

1. Progestin-only ECPs (Plan B One-Step, Next Choice)

Plan B One-Step, and the generic version, Next Choice, contain only progestin.  Plan B requires one 1.5 mg tablet, while Next Choice consists of two tablets taken 12 hours apart.  Like the early Preven, both of these ECPs must be taken within 72 hours (3 days) of unprotected intercourse. They are reasonably effective for up to 120 hours (5 days), but are more effective the sooner they are taken after the contraceptive failure or unprotected sex.

2. ECPs containing ulipristal acetate (ella)

In August 2010, ella, a second-generation pill containing ulipristal acetate (instead of progestin) was approved by the FDA for emergency contraception.  In Europe, it is marketed as ellaOne and has been available there since October 2009.

This single 30 mg dose can be effective up to 120 hours (5 days) after unprotected intercourse.

Emergency contraception medications are the only contraceptive method that can be easily used after intercourse to prevent pregnancy.


Currently, women and men of any age can purchase Plan B, Plan B One-Step, and their generic versions over-the-counter at a pharmacy. However, the two-pill versions of the drug, including Plan B and Next Choice, will still be restricted to those 17 and older without a prescription. Girls under 17 can purchase these from a pharmacist with a prescription from their health care provider.

Ella, the newest emergency contraceptive that works up to 5 days after unprotected sex or birth control failure, is only available by prescription from a nurse or physician. It provides another alternative to preventing unintended pregnancy.

These pills range in price from $10 to $70.  To get insurance coverage for ECPs, you will need a prescription from a health care provider.  Some family planning clinics provide ECPs for a reduced rate or for free to those with low incomes or who do not have insurance coverage.


It is not possible to determine exactly how effective these pills are (since they prevent something that hasn’t happened yet), but if 100 women have unprotected intercourse one time during the second or third week in a menstrual cycle, approximately 8 will become pregnant. Of those same 100 women, only one would be expected to get pregnant if they use Plan B or Next Choice.  So, ECPs are expected to prevent 7 out of 8 pregnancies.5


According to the most recent studies, emergency contraceptives can cause nausea, vomiting headache, breast tenderness, cramps, and fatigue.  These effects usually don’t last for more than a few days after treatment, and they generally resolve within 24 hours.

Emergency contraception has been used by millions of women safely and effectively.  The benefits of using these pills outweigh the risks in all situations.

Women with preexisting medical conditions such as cardiovascular disease, migraines and liver disease or those with previous ectopic pregnancy may use ECPs.  In fact, research has shown that pregnancy poses a greater threat to women with medical problems such as blood clots and liver disease than a 1-day dose of hormones like progestin.

Repeat usage of ulipristal acetate ECs within the same menstrual cycle is not recommended as the safety and efficacy of this type of use has not been evaluated.

Information about emergency contraceptives is easy to find: go to www.not-2-late.com for more information or to find an emergency contraceptive provider near you. The not-2-late web site has no connection to or funding from any of the companies that make emergency contraception.


  1. Finer LB, Henshaw SK. Disparities in rates of unintended pregnancy in the United States, 1994 and 2001. Perspect Sex Reprod Health. 2006 Jun;38(2):90-6  
  2. Lloyd, S. (2012). Controversy surrounding emergency contraception. EmpowHER. Retrieved from http://www.empowher.com/sexual-well-being/content/controversy-surrounding-emergency-contraception?page=0,0  
  3. Office of Women’s Health. (2012). Birth Control Guide. In U. S. Food and Drug Administration (Ed.).  
  4. Trussell, James and Kelly Cleland. (2012). Emergency contraception: How it works (how it doesn’t). Science Friday. Retrieved from http://sciencefriday.com/blogs/06/15/2012/emergency-contraception-how-it-works-how-it-doesn-t.html  
  5. Association of Reproductive Health Professionals. Clinical proceedings: Update on emergency contraception. March 2011. Available at: href=”http://www.arhp.org/uploadDocs/CPECUpdate.pdf”>http://www.arhp.org/uploadDocs/CPECUpdate.pdf. Accessed on 5/3/11  
  6. FDA (February 25, 1997). Certain combined oral contraceptives for use as postcoital emergency contraception. Fed Regist 62 (37): 8610-2.