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Myth No. 1: The Pill makes you gain weight

Reality: The truth is, it might depend on your prescription. In 2011, researchers at the Cochran Database System Review analyzed 49 studies that compared a variety of birth control methods with placebos and found no evidence that birth control causes weight gain. However, a 2009 study in the American Journal of Obstetrics and Gynecology found that women using the Depo-Provera shot gained an average of 11 pounds and increased their body fat by 3.4 percent over three years, though they're not sure what caused this effect. If you're concerned about gaining weight, talk to your doctor about the best option for you.

More: The 3 Biggest Weight Loss Mistakes

Myth No. 2: You don't need to be on birth control if you're breastfeeding.

Reality: This very common myth is totally false -- and probably to blame for many unplanned pregnancies -- says Mary Jane Minkin, M.D., clinical professor of obstetrics and gynecology at Yale University School of Medicine. The truth: breastfeeding exclusively (without supplementing with formula) can suppress the hormones from the pituitary gland that make you ovulate, says Minkin. So while there's certainly a dip in your fertility at this time, it's nowhere near foolproof. "And if you breastfeed sometimes while supplementing with formula, all bets are off," says Minkin.

Myth No. 3: You have to take the Pill at the same time every day.

Reality: Despite what you may have heard, taking the Pill at the same time each day does not make it more effective, says Vanessa Cullins, M.D., Vice President for External Medical Affairs at Planned Parenthood. This common belief is only true if you're taking the mini-pill (a progestin-only birth control pill which must be taken at the same time every day), however the majority of women take the regular birth control pill, which contains a combination of estrogen and progestin. That said, you might want to stick to a strict schedule if you have trouble remembering to take it or if you're on a very low-dose form of the Pill, as you may experience some breakthrough bleeding, says Alyssa Dweck, M.D., co-author of V is For Vagina.

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Myth No. 4: Being on the Pill for a long time will make it harder to get pregnant later.

Reality: It might seem hard to believe, but it's possible to get pregnant as soon as you stop taking birth control, says Minkin. This holds true for all methods of hormonal contraceptives, with the exception of the Depo-Provera shot. It can take up to 6-9 months for all of the hormones in the shot to leave your body before your fertility is restored. That said, it's still possible to get pregnant during this time, so don't count on this buffer period for contraception. The bottom line: Birth control will not screw with your fertility long term, says Minkin.

More: The Truth About Fertility After 35

Myth No. 5: Newer forms of birth control aren't as safe as the older brands.

Reality: You may have heard that newer forms of birth control -- like Yasmin, Yaz, or NuvaRing -- come with more hormones and more health risks than the old standbys. The truth is, the newer the birth control, the fewer hormones it contains, says Minkin. And while some studies have shown a slightly higher risk of blood clots in women taking newer forms of birth control, the increase is extremely low and still much lower than your risk of developing a clot while pregnant, says Minkin.