Emergency Contraception (Morning After Pill)

Considering emergency contraception, aka the morning after pill?

If you’ve had unprotected sex and are considering taking the morning after pill, here are a few things to consider before using this form of contraception.

How does it work?

Pregnancy occurs during ovulation, the phase of the female menstrual cycle when the ovary releases a mature egg which then travels down a fallopian tube toward the uterus. If the egg encounters sperm during the five days leading up to and including ovulation, it becomes fertilized, and a pregnancy begins.
Emergency contraceptives (EC) work primarily by preventing ovulation and therefore the fertilization of the egg. The longer after unprotected sex they’re taken, the less effective they are.

Types of emergency contraceptives

  • Levonogestrel (Plan B One-Step®)

    - Utilizes synthetic progestin.
    - Must be taken within 72 hours of unprotected sex.
    - It is recommended to abstain from sex or use a barrier method for up to 7 days after using Plan B.
    - Should not be used in women weighing over 155 lbs.

  • Ulipristal acetate (ella®)

    - Can be taken within 5 days of unprotected sex.
    - Requires a prescription.
    - Ella® should not be taken twice in the same cycle.
    - It is recommended to use a barrier method of protection for up to 2 weeks after taking ella® as it can decrease the effectiveness of other forms of hormonal birth control.
    - Should not be used in women weighing over 195 lbs.

  • Copper IUD (Paraguard®)

    - Should be placed within 5 days of unprotected sex.
    - Needs to be inserted by a healthcare professional.

Potential Side Effects

  • Nausea
  • Vomiting
  • Headache
  • Irregular periods

A few considerations

Morning-after pills will not work if your body has already started ovulating. This is why timing is so important, especially if you’re using Plan B and other levonorgestrel morning-after pills. (ella works closer to the time of ovulation than levonorgestrel morning-after pills like Plan B.)

Also, if you use an emergency contraceptive, it’s possible that your periods may be irregular in the days to weeks after you take the medication.

As of December 2022, the FDA (Food and Drug Administration) has identified that evidence does not support that Plan B affects implantation (1). According to ACOG (American College of Obstetricians and Gynecologists), “No studies have specifically investigated adverse effects of exposure to emergency contraceptive pills during early pregnancy.” However, studies regarding the teratogenic risk of contraception while taking daily oral contraceptives have found no increased risk for pregnant woman and developing fetus (2). Opinions in the medical community shift with time and further research is needed regarding risks or effects of emergency contraceptives in early pregnancy (when fertilization has already taken place).

Reviewed by Lynn B., BSN, RN


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