Emergency Contraception: The Basics
author: Gregory Paczkowski, MD, MBA
Introduction Emergency contraception is a collection of methods used by women after sexual intercourse to prevent pregnancy. Emergency contraception is not abortion. There are several methods, and differences exist between them in terms of cost, availability, and efficacy based upon the method used and when it is administered after sex.
Currently, nearly half (1) of the pregnancies in the United States are unintended - they’re either unwanted or occur earlier than desired - and approximately 40% end in abortion. Unintended pregnancy poses an enormous challenge to women, children, families, and to society as a whole. Although not a recommend form of birth control, emergency contraception is effective at preventing unintended pregnancy, empowering women to have only the children they want.
What is Emergency Contraception? Emergency contraception is a method taken after sexual intercourse to prevent pregnancy. Four methods of emergency contraception exist in the United States: the copper intrauterine device (Cu-IUD), and three emergency contraception pills (ECPs) - Ullipristal Acetate (UPA), levonorgestrel (LNG) and combined estrogen and progestin in two doses (the Yuzpe method). Mona provides access to LNG and UPA.
Risk Factors for Unintended Pregnancy Many risk factors exist that make unintended pregnancy more likely after sexual intercourse; examples include:
- No contraception was used
- Contraception was used incorrectly
- Condom broke or fell off
- Birth control expired or missed
LNG for Emergency Contraception
Key points:
- Must be taken within three days of unprotected sex
- LNG will not harm an existing pregnancy; it does not cause abortion
- Certain medications and body mass indexes (BMI) make LNG less effective
- Does not protect against sexually transmitted infection
Levonorgestrel (LNG) is an over the counter (OTC) pill that when taken within three days (72 hours) of unprotected sex can prevent unintended pregnancy. It does not cause abortion and does not protect against STIs. LNG works by inhibiting ovulation and delaying follicular rupture. It is approved for any woman in the United States.
Liver enzyme inducers Studies suggest LNG is less effective when taken with certain medications that can alter the drug’s metabolism,(2) decreasing its concentration in the body.
BMI Likewise, studies have found that in women who weigh over 154 lbs or have a BMI of over 26, LNG’s ability to prevent pregnancy may be reduced.
Breastfeeding LNG is safe to take while breastfeeding.
Side effects Side effects may include nausea, vomiting, abdominal pain, headache, breast pain, and temporary menstrual changes.
Aftercare pregnancy testing is recommended if, after taking LNG, the next menstrual period in your cycle is delayed by more than seven days, is lighter than usual, or you feel unusual abdominal pain.
If you vomit within 2-3 hours of taking LNG, we recommend taking a second dose.
We recommend starting a regular form of birth control after taking LNG to prevent the need for future use of emergency contraception, because it is not as effective as regular contraception (the pill, the patch, the ring, an IUD or subnormal implant) at preventing unintended pregnancy.
UPA for Emergency Contraception
Key points:
- Must be taken within five days of unprotected sex
- Requires a prescription
- Does not protect against STI
- Not safe while breastfeeding
- Certain medications and body mass indexes (BMI) may make UPA less effective
Ulipristal acetate is prescription medication that when taken within five days (72 hours) of unprotected sex can prevent unintended pregnancy. It does not cause abortion and does not protect against STIs. UPA is a synthetic progesterone agonist/antagonist; it works by inhibiting ovulation and delaying follicular rupture. It also alters the endometrium, affecting implantation.
Liver enzyme inducers Studies suggest UPA is less effective when taken with certain medications(3) that can alter the drug’s metabolism decreasing its concentration in the body.
BMI Limited evidence suggests that women with a BMI greater or equal to 30 may experience an increased risk for pregnancy after use of UPA; other studies have found no such increase.
Breastfeeding Breastfeeding is not recommended for 24 hours after taking UPA because it is excreted in breast milk. Breast milk should be expressed and discarded for 24 hours after taking UPA.
Side effects Side effects may include nausea, vomiting, abdominal pain, headache, breast pain, and temporary menstrual changes.
Aftercare pregnancy testing is recommended if, after taking UPA, the next menstrual period in your cycle is delayed by more than seven days, is lighter than usual, or you feel unusual abdominal pain.
If you vomit within 2-3 hours of taking UPA, we recommend taking a second dose.
Initiation or resumption of progesterone-containing hormonal contraception should be delayed at least 5 days after taking UPA and a barrier method of contraception like a condom should be used until the next menstrual period.
Intrauterine device (IUD) for Emergency Contraception
Key points:
- Both the copper TCu380A IUD (Paraguard) and levonorgestrel 52 mg IUD (Mirena) can be used as emergency contraception with five days of unprotected sex.
- Requires a doctors visit for insertion
- Does not protect against STI
Two types of IUDs exist that are effective methods of emergency contraception. Mirena îs inserted into the uterus, where it releases a hormone that prevents pregnancy by thickening the mucus in the cervix to stop sperm, thins the lining of the uterus, and partially suppresses ovulation. Paraguard is also inserted into the uterus, but does not contain hormones. Instead, it uses a small amount copper, which is toxic to sperm, to prevent sperm from reaching the egg.
BMI Paraguard for emergency contraception shows no evidence of impaired efficacy in women with BMI greater than 30
Breastfeeding Both Mirena and Paraguard are safe to use while breastfeeding
Aftercare Both IUDs provide ongoing contraption, with no need for an interval or backup contraception after insertion. The copper TCu380A (Paraguard) IUD, if left in place, provides at least 10 years of reversible contraception. The levonorgestrel 52 mg (Mirena) IUD, if left in place, provides six years of reversible contraception.
Combined oral estrogen and LNG contraceptive pills (Yuzpe method) for Emergency Contraception
Key points:
- Some birth control pills can be used as emergency contraception
- Most effective if used within 3 days (72 hours) of unprotected sex
- Does not protect against STIs
- Not as effective as IUD, UPA, or LNG
The Yuzpe method is an alternative form of emergency contraception that relies upon using the birth control a woman already has. Using 100 mcg of ethinyl estradiol and 0.5 to 0.6 mg of LNG or norgestrel in two separate doses 12 hours a part can be an effective for preventing pregnancy. It only works with certain brands of combined oral contraceptives - check to see if your pill can be used as emergency contraception.(4)
Side Effects some women experience nausea and vomiting when using this method. Side effects associated with the birth control used are also possible, including but not limited to spotting, breast tenderness, headaches.
Aftercare pregnancy testing is recommended if, after taking LNG, the next menstrual period in your cycle is delayed by more than seven days, is lighter than usual, or you feel unusual abdominal pain.
If you vomit within 2-3 hours of taking LNG, we recommend taking a second dose.
References
- https://pubmed.ncbi.nlm.nih.gov/26962904/
- antiepileptics: carbamazepine, eslicarbazepine, oxcarbazepine, phenobarbital, phenytoin, primidone, rufinamide topiramate; antibiotics: rifabutin, rifampicin; antidepressants: st John’s wart; others: modafinil, bosentan, aprepitant, efavirenz (HIV medication)
- strong CYP3A4 inducers: bosentan, carbamazepine, felbramate, griseofulvin, oxcarbazepine, phenytoin, rifampin, St. John’s wart, topiramate, efavirenz, lumacaftor
- https://www.bedsider.org/features/88-the-yuzpe-method-effective-emergency-contraception-dating-back-to-the-70s