32 Longstanding Health Myths That Need to Go Away

About 80 years ago, the world watched in horror as Scarlett O'Hara fell down a flight of stairs and lost her baby in Gone With the Wind. And ever since, you've probably thought that a tumble like that could trigger a miscarriage. Well, probably not, says Mary Jane Minkin, MD, a clinical professor at Yale University School of Medicine. But we're getting ahead of ourselves.

Sometimes, it's hard to remember where we've heard some surely well-intentioned piece of health advice. But whether you get most of your info from a juicing roommate, online blog post, or even your parents, chances are that you believe something you shouldn't. But now we're setting the record straight. Here are 32 myths about women's health, nutrition, weight loss, fitness, conditions, and sleep that you should stop believing now.

"I hear this regularly," says Dr. Minkin. "It's been around for probably the last 40 years." But the truth is, once you stop taking the pills, you can get pregnant because your body is no longer receiving that extra dose of pregnancy-preventing estrogen or progestin hormones, she says.

(Remember, it's even possible—though very rare—to get pregnant while taking birth control. According to the National Institutes of Health, an estimated 2 or 3 women out of 100 may become pregnant while on the pill—even if they never miss a dose.)

Dr. Minkin says that she's seen women get pregnant a week or two after they stop taking the pill. And one 2009 study published in the journal Obstetrics & Gynecology found that about 20% of women were able to get pregnant one cycle after they stopped using birth control.

We're not sure where this one came from, but it's definitely out there: According to a 2014 study published in the journal Fertility & Sterility, about 40% of women think that if you lie on your back with your pelvis elevated, you'll increase your odds of getting pregnant. (You might also have heard the reverse: If you stand up after sex, you'll minimize the chances of getting pregnant.) "[It’s] probably just the thought that gravity could work in your favor," says study author Jessica Illuzzi, MD, an associate professor of obstetrics, gynecology, and reproductive sciences at Yale University. Alas, it doesn't work: "As long as the semen is released into the vagina, the sperm can usually find their way up the cervix, into the uterus, and into the Fallopian tubes."

Not exactly. "The average cycle is every 28 days, which is every 4 weeks," says Dr. Illuzzi, "so every month is an easy way to think about it." But a normal menstrual cycle occurs every 25 to 35 days, so if you're on the shorter or longer end of that spectrum, you might have, say, a flow-free February—or a twofer. Even an occasionally irregular period is pretty common, says Dr. Minkin. If you're regularly long or short, it's a good idea to check with your doctor about your periods, but don't start stressing.

What you're born with is what you get. Still, nearly 40% of women in the Yale University survey think that women keep making eggs throughout their lifetime. "Since men make new sperm for each ejaculation, it is not surprising that people might think we 'produce' new eggs with each ovulation," says Dr. Illuzzi.

Females are born with an estimated 1 million egg cells (oocytes), according to the American College of Obstetricians and Gynecologists. By the time we reach puberty, all but about 300,000 have wasted away. Each month, about 20 eggs start to get ready for ovulation, but usually only one—the biggest, and the one with the most hormone receptors—will 'win' the contest and actually ovulate. As we age, the eggs die off, and the cells break into small bits and are absorbed by the body. Overall, about 300 of the eggs are released by the ovaries during the reproductive years.

Miscarriages might be fairly common. According to the latest data from the CDC, there were about 1 million miscarriages—about 17% of all pregnancies—in 2010 alone. "When you start asking women about their histories, this comes out," says Dr. Minkin.

But that's not conventional wisdom by any means. In fact, most people believe that miscarriages occur in fewer than 5% of all pregnancies, according to a 2015 Albert Einstein College of Medicine survey of more than 1,000 people. (Contrast that with the 15% of people in the survey who actually had a miscarriage.) The belief that miscarriages are rare is a big problem, say the researchers, especially because 40% of all people who had one feel guilty, or that they did something wrong.

Miscarriages are rarely ever related to a traumatic event, says Dr. Minkin. But according to the 2015 survey, 76% of people believe that you can have one from experiencing a stressful event and 64% say that lifting a heavy object can trigger one too.

"The vast majority of miscarriages [happen when] the embryo, which is formed from that sperm and egg, is not genetically perfect," says Dr. Minkin. "Mother Nature says, let's try again." And, as Dr. Minkin points out, "If you have had a miscarriage, you have no increased chance of having another."

About 1 in 5 women reported douching (i.e., washing or soaking the inside of the vagina) in the past year, according to 2011-2013 CDC data. But there's no medical reason do this, says Dr. Minkin. In fact, douching can alter the delicate balance of bacteria that keep your vagina healthy, making the area less acidic (a bad thing) and prone to infection, dryness, and irritation. "The vaginal tissue is the most sensitive in the body," says Minkin. Even scented products, which can contain perfumes, can irritate you down there. Bottom line: Your vagina is perfectly capable of cleaning itself, thanks.

A douche is not a contraceptive. Douches can throw off the balance of good bacteria in your vagina, but it won't do a thing to prevent sperm from making a beeline toward your egg. If you're looking for an emergency contraceptive, talk to your doctor about other options, like Plan B, an over-the-counter drug that prevents the ovary from releasing an egg.

Speaking of emergency contraceptives, this one has lingered for years. Some background: An abortion is the termination of a pregnancy, either via a procedure or a medication. (Currently, the only FDA-approved pill for this purpose is called Mifeprex, which is available with a prescription and can be used within the first 49 days of pregnancy.)

Plan B One-Step is different. It does not cause an abortion, nor will it terminate an existing pregnancy. It works mainly by stopping the ovary from releasing an egg, but it's also possible that it works by preventing sperm from fertilizing the egg or preventing the embryo from attaching to the uterus. And while women under the age of 17 needed a prescription to buy it in the past, they don't anymore: In 2013, the Food and Drug Administration (FDA) ruled that women of all reproductive ages no longer needed a prescription to take the over-the-counter medication.

Experts have long been baffled about where this myth came from. One 2002 paper in the American Journal of Physiology combed the literature and couldn't find any scientific evidence that backed up this theory. One guess, according to the authors, was a 1945 report written by the Food and Nutrition Board of the National Research Council that said: "A suitable allowance of water for adults is 2.5 liters [about 10 cups] daily in most instances... Most of this quantity is contained in prepared foods." Emphasis on that last part.

In fact, there's no rule that you have to get all your fluid intake from water alone, says Marie Spano, RD, a sports nutritionist. You can get plenty from food. "Soups, fruits, and vegetables absolutely count," she says.

You've probably been told that not only will coffee not keep you hydrated, but that since caffeine is a diuretic, you should drink extra water to compensate. But as it turns out, if you're a habitual coffee drinker, you can go ahead and count that venti Americano to your daily fluid intake. In a 2013 study by researchers from the University of Bath, people who drank moderate amounts of coffee a day (which contained a range of about 200 to 450 milligrams of caffeine) weren't any more dehydrated at the end of 3 days than those who just drank water. While caffeine itself can act as a diuretic, say the study authors, people likely build up a tolerance, which makes them able to stay hydrated.

RELATED: 5 Reasons You're Tired All the Time

Experts have known for years that tryptophan—an amino acid found in turkey—can make people feel sleepy. But the thing is, plenty of other foods, like pork, lamb, and beef, contain about as much tryptophan as turkey, and we don't think those make us sleepy, says Spano. As for why you crashed on your grandma's couch after Thanksgiving dinner? Blame all the carbs and sugar you just ate. (Immediately sitting down to watch the football game probably didn't help either.)

This one has even worked its way into the current dietary guidelines, which advise people to eat a nutrient-dense breakfast every morning. And to be sure, plenty of association studies have found that those who eat a morning meal tend to have lower BMIs than people who skip it. (Theory goes, if you deprive yourself of food in the a.m., you'll overeat later on in the day.) But causation doesn't equal correlation, says Spano, and other factors (like a healthier overall diet and more physical activity) may also help keep regular breakfast eaters stay slim. When one 2014 study in the Journal of Nutrition Science found that overweight people who skipped breakfast for 4 weeks ended up losing weight compared to those who ate oat porridge, people started to wonder whether eating first thing in the morning was as important as we've been told. There's nothing wrong with having a nutritious breakfast, says Spano, but forgoing it doesn't necessarily set you up for weight gain, either.

This one has even worked its way into the current dietary guidelines, which advise people to eat a nutrient-dense breakfast every morning. And to be sure, plenty of association studies have found that those who eat a morning meal tend to have lower BMIs than people who skip it. (Theory goes, if you deprive yourself of food in the a.m., you'll overeat later on in the day.) But causation doesn't equal correlation, says Spano, and other factors (like a healthier overall diet and more physical activity) may also help keep regular breakfast eaters stay slim. When one 2014 study in the Journal of Nutrition Science found that overweight people who skipped breakfast for 4 weeks ended up losing weight compared to those who ate oat porridge, people started to wonder whether eating first thing in the morning was as important as we've been told. There's nothing wrong with having a nutritious breakfast, says Spano, but forgoing it doesn't necessarily set you up for weight gain, either.

Not exactly. The formula itself came from a 19th-century Belgian polymath named Adolphe Quetelet, but it was popularized by a scientist named Ancel Keys in the mid-20th century. Since then, it's been one of the most widely used tools in determining if a person not only has a normal weight, but is in good health.

But while the formula has some benefits, it also has its share of limitations—mainly that it doesn't distinguish between muscle and fat, nor can it tell where a person's fat is distributed. "It's become misused over the years," says Spano. And one 2007 study from Michigan State University researchers found that BMI wasn't a very effective tool to measure both college athletes and non-athletes—and that scientists should try to find a different way to classify these people as being overweight.

Starting in the 1930s, there was the Grapefruit Diet. Now, it's Paleo. And in between, everyone from scientists, to nutritionists, to our totally reputable friends-of-friends have championed low carb diets, low fat diets, the South Beach Diet, Weight Watchers, and more. And while it seems like we've exhausted all the options, we aren't any closer to determining the winner.

To solve this mystery, researchers from Yale University examined seven different diets (including low fat, low carb, vegan, Mediterranean, mixed, low Glycemic, and Paleo) and found that they all had a mixture of pros and cons. They also found that they couldn't label any of them the best one for a person's health. There's a saying that the best diet is the one you'll stick to, says Spano. And, in fact, the Yale researchers concluded that perhaps the best "diet" is a pattern of eating minimally processed, mostly plant foods. Sounds like something we can handle.

It's smart to wear sunscreen all the time, especially in the car or if you sit near a window. Here's why: The sun contains UVA and UVB rays, both of which play a role in skin aging, eye damage, and skin cancers, according to the Skin Cancer Foundation. And while UBV rays (which are responsible for giving you a sunburn) don't penetrate window glass, UVA rays do—and they can also cause skin damage way down in the skin's epidermis. One 2011 study in the Journal of the American Academy of Dermatology found that 52% of melanoma cancers are found on the left side of the body; the researchers suspect that this is partly because in the United States, drivers' left sides face the window.

"Just because you don't have a sunburn doesn't mean the sun isn't damaging your skin, says Filamer Kabigting, MD, a dermatologist at ColumbiaDoctors.

Makeup is a good added layer of protection, but it shouldn't be your only line of defense. If you're going outdoors, you should choose a sunscreen with at least an SPF 30, according to the American Academy of Dermatology. When you're out in the sun, you also need to apply it evenly on your face every 2 hours—something that's not really feasible with makeup alone, says Dr. Kabigting. And don't forget your lips. Compared to the rest of your skin, your lips contain low levels of melanin—the pigment helps protect against UV damage—so they're especially sensitive to the sun. Use a lip balm with SPF 30, suggests Dr. Kabigting.

This one's a little misleading. For example, a sunscreen with an SPF of 15 will protect against 93% of the sun's rays, while SPF 30 and SPF 50 filter out 97% and 98%, respectively. And there's no proof that anything higher is any more protective against sun damage. "There's a lot of confusion out there about SPFs," says Dr. Kabigting. That's one reason why the FDA proposed a regulation that would limit manufacturers to a label of "SPF 50+."

The bigger problem, Dr. Kabigting says, is that people don't wear enough sunscreen in the first place. If you're going outside, slather on 1 ounce of water-resistant, broad-spectrum sunscreen with at least an SPF of 30. And remember to reapply at least every 2 hours.

It's true that people with darker skin are less likely to get skin cancer than those with lighter skin. The American Cancer Society says that 1 in 1,000 African Americans will develop melanoma (the most dangerous type of skin cancer) in their lifetime compared with 1 in 200 Hispanics and 1 in 40 Caucasians. Part of the reason is because darker skin contains more melanin, a pigment that helps protect against the harmful effects of the sun's rays. The Skin Cancer Foundation says that African Americans' skin may be equivalent to an SPF 13.4 protection; Caucasians may be an SPF 3.4.

But not only are African Americans and Hispanics more likely to die of melanoma within a 5-year time period, their cancers also tend to be thicker and more aggressive than Caucasians', according to a 2009 review. That's possibly because their tumors are found at a later stage, says Dr. Kabigting.

The theory makes sense. Since you haven't eaten anything yet, you'll burn off the calories from your fat reserves. Right? Well, it can work differently in real life: In a 2014 study in the Journal of the International Society of Sports Nutrition, researchers asked a group of women to do 1 hour of aerobic exercise three times a week for a month. Half of the women worked out after an overnight fast, while the other half worked out an hour after they ate a meal. At the end of the experiment, both groups lost weight—and neither group had an advantage over the other.

"The human body is highly complex," explains study author Brad Schoenfeld, PhD. "It's therefore misguided to simply look at fat-burning in a vacuum." Plus, he adds, people can burn calories from the fat in their muscles (yep, that's a thing), which wouldn't improve your physique anyway.

Conventional wisdom tells you that if you want to maximize muscle growth, you need to eat protein immediately after your workout and that you have only a 30-minute window of time to do so. But Schoenfeld's research shows that timing isn't as important as you might think. In fact, his own study found that people can consume protein at any point during the 5 to 6 hours that span the workout and still get the muscle-building and recovery benefits. "The window exists on a spectrum. It's not as if the window closes and you don't get any benefits. Rather, there seems to be a gradually diminishing impact on muscular gains the longer you go past the threshold," he says.

And remember: Refueling an hour after a workout doesn't mean license to go overboard.

Anyone who's a fan of cardio machines is familiar with the term. But what does it really mean? Let's say you're working out on the treadmill—well, getting into the "fat burning zone" means that you're burning a higher percentage of your calories from fat.

But if you want to lose weight, there are more important things to consider: "The ultimate driver of fat loss is total fat burned both during and after exercise," says Schoenfeld. And one of the best ways to do that is with high-intensity interval training (HIIT), which alternates short periods of intense exercise with lighter ones.

We can credit that myth's staying power with the notion that women will bulk up if they lift heavy weights. (They won't, mainly because they have higher levels of estrogen, which prevent this.) Instead, a regular strength training routine can help prevent women from gaining body fat as they age, according to one 2-year study in the journal Nutrition.

For the record, says Schoenfeld, lifting very light weights to the point where you're fatigued could certainly increase muscle mass. For the record, says Schoenfeld, lifting light weights to the point where you're fatigued may bulk you up just as much as lifting very heavy weight for fewer reps.

When doctors can no longer detect any visible cancer cells, then the disease is said to be in remission, not "cured." That's because it may return in the future. (Some can return within 5 years, others may take longer.)

Doctors try to determine whether the cancer is gone with tests like a CT scan or a bone marrow biopsy. "But they can't guarantee that none of the cancer cells have spread and set up shop somewhere else in the body," explains Brian Till, MD, assistant member of the clinical research division at Fred Hutchinson Cancer Research Center. Technology is getting better, but right now tests can only detect clusters of cells, not single ones. "It's like trying to find a single grain of blue-green sand on a white beach," he says.

Think the flu is just a trivial illness? If so, you probably aren't alone. Only about 1 in 3 U.S. adults aged 18 to 49 got a flu shot in the past 12 months, according to 2014-2015 statistics from the CDC.

But the truth is, influenza is a serious illness, says Susan Rehm, MD, vice chair of the department of infectious disease at Cleveland Clinic. Not only did about 3,700 people die of influenza in 2013, according to national statistics, but a 2004 study in the Journal of the American Medical Association estimated that there about 200,000 hospitalizations a year in the United States due to flu complications.

The shot is made with an "inactivated" virus, so it can't trigger the illness. "The virus is killed," explains Dr. Rehm. After the shot, your immune system will recognize the bits of proteins that still remain in the dead virus and start gearing up to fight them should you ever encounter a real flu bug. "It's like a practice run," she says.

That said, there can be some side effects, like swelling, redness, and soreness—"a good thing," says Dr. Rehm, since the vaccine is "working." But what happens if you come down with the flu a few days after you had the shot? Well, it takes about two weeks before the vaccine's protection kicks in—and during that time, you may have already caught the flu. Then, there's a slight chance that the vaccine wasn't effective—which can happen, since the virus is constantly evolving throughout the season. "We know the vaccine isn't 100% effective," says Dr. Rehm, "but if you don't get it, then you have zero protection."

The takeaway? There's a chance you could come down with the flu after you get the shot—but the shot itself won't be the reason you got it.

Actually, if you're pregnant, you should definitely roll up your sleeve. (Same goes if you're breastfeeding.) Not only is it safe, but national health organizations say that pregnant women should get the flu shot no matter what trimester they're in.

That's because pregnant women's bodies undergo changes in their immune and respiratory systems, which increases their risk of becoming seriously ill from the flu. Pregnant women are also more likely to be hospitalized from flu complications. This was especially true during the 2009 influenza A (H1N1) season, where pregnant women had a much greater chance of dying from the flu, according to one 2010 study in the Journal of the American Medical Association.

About two weeks after you get the vaccine, your body will start producing antibodies that will help protect you and your unborn baby from the flu—even up to 6 months after the child is born.

It's true that as we age, we sleep less—but as for whether we need less sleep? That's still up for debate, says Meena Khan, MD, a clinical assistant professor of neurology who specializes in sleep medicine at the Ohio State University Medical Center. "It's a trend, but no one really knows why." What is known is that people over the age of 65 are more likely to have sleeping problems like insomnia, which could set them up for a scary fall during the daytime.

Regardless of your age, "no one should get less than 6 hours of sleep a night," says Dr. Khan. It's okay to take a nap, she explains, but it's good to keep it to around 20 minutes. Any longer than 30 minutes, and you start getting into slow-wave sleep, and when you wake up, you might feel groggy.

That might work once in a while, says Dr. Khan, but if you're chronically sleep deprived, you can't expect to make up a deficit by logging a few extra hours of shuteye on Saturday morning. For starters, let's say you function best on 7 hours a night, but you're consistently getting 5 hours on weekdays. Add up all the hours you've missed out on and that means you need to sneak in an additional 10 hours on the weekend. Good luck with that.

Plus, the effects of too little sleep might have more immediate consequences, particularly on your waistline: One 2008 study in the American Journal of Clinical Nutrition found that when people slept less than 6 hours a night, they ate more calories in snacks the next day, even though they ate the same amount at mealtimes.

As many as 13% of men and 6% of women in are estimated to have moderate to severe sleep apnea, according to a 2013 study in the American Journal of Epidemiology. With sleep apnea, the upper airway collapses, sometimes dozens of times a night, triggering high blood pressure, daily fatigue, and other problems. That's a double-digit increase from previous estimates, say the study authors. So while the disorder is more common in men, more and more women may be getting it too, partly because as a society, we're becoming more overweight. Plus, women's risks increase after menopause, says Dr. Khan, perhaps because they experience a drop in estrogen that leads to the weakening of certain muscles in the upper airway. And while snoring is a common sign of sleep apnea in men, women commonly report feeling fatigued during the day. The good news is that treatment can reduce your risk of high blood pressure and other problems associated with sleep apnea.

It's true that a nightcap can help you fall asleep faster, but you won't wake up feeling refreshed the next morning. That's because drinking alcohol before bed disrupts the second half of your sleep, preventing the amount of time you spend in restorative (or REM) sleep mode, according to a 2014 study by researchers from the University of Missouri. Your sleep is also more fragmented, and you can wake up more often in the middle of the night, says Dr. Khan.