Understanding the different types of emergency contraception and how to choose which is best for you

• The different types of emergency contraception include Ella, Plan B, birth control pills, and the copper IUD.
• To choose the best type of emergency contraception for you, it's important to consider how long it has been since you had unprotected sex, your weight, and if you need a prescription.

While regular use of contraceptives is the best choice to prevent pregnancy, emergency contraception is a safe way to prevent an unwanted pregnancy after having unprotected sex.

If you've recently had unprotected sex and are looking for emergency contraception your main options are:

• Plan B
• Ella
• Copper IUD
• Yuzpe regimen

Here's a breakdown of the pros and cons of each type and how to choose the best emergency contraception for you.

Levonorgestrel morning-after pills

Levonorgestrel is a synthetic hormone that stops the release of the egg from the ovaries to prevent fertilization, says Julie Levitt, MD, a gynecologist at The Women's Group of Northwestern. While there are several popular brands, including Plan B One-Step, My Way, and After, the effectiveness is the same no matter which pill you take.

When can I use it? You can use levonorgestrel for up to 72 hours (3 days) after unprotected sex, but it is best to take the pill as soon as possible for better efficacy.

How effective is it? Numerous studies have found levonorgestrel to be 60% to 94% effective in preventing pregnancy depending on how soon you take the pill.

Do I need a prescription? No, you can buy the pill over the counter and most pharmacies or drug stores carry it.

Ella (ulipristal acetate)

Ella is an emergency oral contraceptive that contains a drug called ulipristal acetate. While it does not contain estrogen or progesterone, it is a single-dose steroid medication. Taking a single tablet prevents ovulation, delaying a woman from releasing the egg from her ovary.

When can I use it? Ella is effective up to five days (120 hours) after unprotected sex. Like the copper IUD, this method does not diminish over time, but it is best to take it as soon as possible to avoid ovulation. If you vomit within three hours after taking the pill, ask your medical provider whether you should take another one.

How effective is it? It's around 65% to 85% effective at preventing pregnancy depending on how soon you take the pill, says Bartz.

Do I need a prescription? Yes, you need a prescription for Ella. There are some certified online prescription services or contact your doctor as soon as you can after unprotected sex.

Copper IUD

A copper intrauterine device, or IUD, is a small T-shaped frame that is inserted into the uterus. The device contains no hormones and instead copper keeps sperm from the egg, preventing pregnancy from occurring. This makes it a good option for those who are sensitive to hormonal side effects or can't use hormones due to medical conditions. The copper IUD can provide up t

When can I use it? You can use a copper IUD as emergency contraception up to five days (120 hours) after unprotected sex, but some studies have found it can be effective up to 10 days after.

How effective is it? The copper IUD is the most effective emergency contraception, says Deborah Bartz, MD, MPH, a gynecologist at Brigham and Women's Hospital in Boston, MA. It is over 99% effective in preventing pregnancy and works just as effectively on day one as day five.

Do I need a prescription? No, you do not need a prescription, but a copper IUD must be inserted by a medical professional, such as a women's doctor or nurse. It may be challenging to rely on this method because it requires a prompt appointment.

Birth control pills (Yuzpe regimen)

Birth control pills are an oral contraceptive that contains the hormones estrogen and progestin, which prevents pregnancy by blocking the release of the egg from the ovaries. While these pills are normally taken as a form of daily birth control, they may be also used as emergency contraception after unprotected sex. This is known as the Yuzpe regimen.

There are many different types of birth control pills - some with hormone levels that change each week, others with a steady dose daily. For this reason, the exact number of tablets to take for the first dose may vary, and a second dose is generally taken 12 hours later.

The exact dosage needed in total is 200 mcg Ethinyl estradiol - the estrogen component - and 1 mg progesterone. However, it is not recommended that you do this independently due to the irregularity of the dosing and the high possibility for side effects. Speak with your OBGYN to determine if this is the right method for you to pursue.

When can I use it? The Yuzpe regimen is effective up to 72 hours (3 days) after unprotected sex, but it is recommended to use only if the other contraceptive methods are not readily available. You should also only use it under the direction of a healthcare provider.

How effective is it? Much like the other oral contraceptives, the longer you wait to take the birth control dose, the less effective the method will be. The American College of Obstetricians and Gynecologists no longer recommend this method because it is the least effective (with an average of 74% effectiveness) and has high side effect risks, such as nausea and vomiting.

Do I need a prescription? Yes. You can get a prescription from a healthcare professional, such as an OBGYN, a physician at a Planned Parenthood, or a licensed pharmacist.

Which type of emergency contraception is right for me?

When considering which emergency contraception to use, there are some factors to keep in mind.

When you last had sex: Non-hormonal contraceptives, i.e. Ella and the copper IUD, can work up to five days after, or possibly longer, while most hormonal options - plan B and the pill - are limited to 72 hours.

Weight: If you weigh more than 155lb, pills containing levonorgestrel, like plan B, may be less effective, and you should ask your doctor for an Ella prescription. However, if you weigh over 195 lbs, Ella may not be as effective.Weight has no effect on the copper IUD.

What research says: A 2015 study found that the rate of pregnancy in women over 165 lbs increased significantly (5% to 6%) when taking levonorgestrel. Another large 2012 study found the rate of pregnancy in obese women increased by 7% when taking ulipristal acetate.

Affordability and accessibility: Generally, contraceptives with levonorgestrel are the easiest to find. Meanwhile, Ella is less common in pharmacies and requires a prescription.

Planned Parenthood can be an affordable option for emergency contraception, says Levitt, since they are able to provide care at a lower cost. The organization also has a nifty quiz you can take to determine which emergency contraception is right for you.

Insider's takeaway

Emergency contraception after unprotected sex can come in non-hormonal and hormonal options that vary in effectiveness and method. Choosing which is best for you can depend on various factors, such as weight, when you last had sex, and accessibility, and should be discussed further with your healthcare provider.

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