Hungry for sex advice you can trust? Each week the resident sex experts at Good in Bed will answer your most burning question. Go on, ask 'em anything.

Your Sex Question: What's the deal with the new morning after pill, Ella?

What Anna From Good in Bed Had to Say:

Emergency contraception -- what a lovely thing! First, let's clear something up: The "morning-after pill" is really a misnomer. Emergency contraception (E.C.) -- like the new Ella pill just approved by the FDA -- works within five days of unprotected sex; Plan B, which currently exists, works within 72 hours.

What are the differences? Ella is available by prescription only, and it blocks the hormone necessary for pregnancy to occur. Its effectiveness is the same on any of the five days you might choose to use it.

Plan B is available to folks over the age of 17, "behind the counter," without a prescription. It's one pill, and it's basically a high dose of the hormones that are in birth control pills, so that it prevents an egg from being released. You use it when plan A fails, like when a condom breaks, you forget to take your regular birth control, non-consensual sex happens -- that sort of thing. And the sooner you take it, the more effective it is.

E.C. isn't something you'll want to take often. It disrupts your cycle, there can be side effects, it's expensive (around $40), and, well, wouldn't you rather have a more regular and surefire way to make sure you're not going to get pregnant?

So, let's say you've had unprotected sex. You're going to want to get to the pharmacy and get E.C. as soon as possible. It's effective within 72 hours, but the sooner you take it, the more likely it is that it'll work. If you're already pregnant, or a zygote (sperm + egg) has already been formed, it's not going to cause a miscarriage. This is not the same thing as the abortion pill, the one that causes a miscarriage.

It also doesn't do anything to protect you from sexually transmitted infections, so you're going to want to get to your doc to get tested once enough time has passed. Two tips: First, if you're having sex with men, it's a good idea to have a packet of E.C. around just in case, so that you won't have to stress out and run around looking for it if your usual contraception ever does fail; second, go ahead and talk to your doc about the best birth control for you. It's always more favorable for plan A not to fail than to have to resort to Plan B.

Anna is completing her master's in public health with a focus on sexuality and health at Columbia University. She has an extensive background in safer sex, HIV and STI prevention, and reproductive rights. She has worked with youth and women of all ages, with a focus on empowering others to take responsibility for and control of their emotional and sexual health. She received her undergraduate degree from the University of North Carolina at Chapel Hill, where she created and implemented the now-annual Orgasm Awareness Day. Anna can be reached at Good in Bed.