Whats less clear, however, is how emergency contraception actually works to prevent that pregnancy.
Now, lets get into how each one works to prevent an unintended pregnancy.
This is how levonorgestrel-based emergency contraception works.
Marina Esmeraldo
Plan B One-Step and its generics are made up of a single pill containing thefull 1.5-milligram dose.
The difference, of course, is the dose.
This medication works by delaying or preventing ovulation.
But what if you could delay ovulation so that theres no egg around for the sperm to fertilize?
Levonorgestrel appears to make this happen by mimicking the increased levels ofprogesteronethat normally occurin the days after ovulation.
Worth noting: Some research shows that levonorgestrel may be less effective for people with high BMIs.
Also, as previously reported in anin-depth SELF articleon the subject, less effective doesnt necessarily mean noteffective.
The most crucial factor when it comes to effectiveness is how soon you take levonorgestrel after sex.
Despite the nickname the morning-after pill, you should take levonorgestrel as soon as possible after unprotected sex.
At that point, the release of an egg is imminent, which increases the odds of pregnancy.
However, if you vomit within two hours of taking levonorgestrel, you may need to take another dose.
Call your health care provider to ask their opinion.
This is how ulipristal acetate works to prevent pregnancy.
It also works by hampering ovulation, but in a different way than levonorgestrel.
Ulipristal acetate is designed to be taken within 120 hours (five days) of unprotected sex.
Unlike levonorgestrel,its efficacy does not decreasesignificantly over that time period.
Ulipristal acetate … continues to delay follicular rupture closer to the time of ovulation, Dr. Raine-Bennett explains.
Vomiting within three hours of taking ulipristal acetate warrants a call to the doctor for the next steps.
Firstly, you need a prescription.
Theres really no good medical reason, Dr. Fok says.
The best explanation is that ulipristal acetate is newer to the market.
(The FDA approved levonorgestrel as emergency contraception in 1999 and ulipristal acetate in 2010.)
This is how the copper IUD works to prevent pregnancy.
Finally, we cant talk about emergency contraception without discussing thecopper intrauterine machine(IUD).
Weight also doesnt impact its efficacy, Dr. Bullock adds.
However, copper IUDs do notdisruptimplantation of a fertilized egg that has already occurred, according toACOG.
The main points of consideration for a copper IUD are the price, insertion process, and side effects.
Depending on your insurance, a copper IUD can bemore than $1,000.
Thats because the success of emergency contraceptive pills is so dependent on one instance of delaying or preventing ovulation.
Birth control may do this withestrogento (much more reliably) suppress ovulation.
Some modes of birth control haveboth estrogen and progestin, making use of all of these mechanisms.
Also remember that aside from the copper IUD, these methods workafterunprotected sex, not before it.
If youhave sex after taking oral emergency contraception, you are still at risk of getting pregnant.
Its also worth noting, she says, that none of these methods protect againstsexually transmitted infections.
But, listen, things happen.
And, fortunately, emergency contraception exists for those moments.
