A pregnant woman sitting on the bed and holding her belly.

When it comes to pregnancy, there are a plethora of ‘old wives tales’ floating around. And, in modern times, such tall tales have fueled parent-shaming on social media, causing unneeded pain and pressure.

“Try not to get caught up with the Internet and what others say, and focus on yourself and your baby,” says Joey England, MD, Maternal-Fetal Medicine specialist affiliated with Children’s Memorial Hermann Hospital in the Texas Medical Center.

“If you’re unsure, seek medical advice,” she says of the faux news that litters the web.

Here Dr. England sorts through pregnancy fables to determine what’s fact and what’s fiction.

Coffee could cause a miscarriage.

False. But that doesn’t mean you can java your way through the day. “Caffeine does cross the placenta, so less than 200 milligrams of caffeine daily is recommended,” says Dr. England.

That’s a little more than the amount in a cup of coffee, which is eight ounces. And size matters. A short Starbucks® coffee has 180 mg, while a Venti crams in 475 mg.

Other sources of caffeine matter, too. Red Bull has 10 mg per oz., while just 2 ounces of 5-Hour Energy tops out your day’s total. A Starbucks Chai Latte Grande has 95 mg, while most bottled teas have around 40 mg. A 12 oz. can of soda typically has around 45 mg.

“It’s important to look at package ingredient lists, which can be found online,” Dr. England says.

Your feet will expand.

True. Sadly, feet widen and swell during pregnancy. Pregnancy may not be the best time to buy those Jimmy Choos and Christian Louboutins.

“Each foot has 26 bones and over 30 joints that are held together with ligaments. Just like the ligaments in your pelvis, that connective tissue relaxes, due to hormones,” Dr. England says. “Weight gain also contributes, as does swelling in the third term.”

You can help your feet with cardiovascular exercise, compression hose and pregnancy massages. Also elevate your feet when possible.

Dying your hair will endanger your baby.

False. The dye itself won’t endanger you or your baby, but you should sit in a well-ventilated area and turn on a fan, to make sure you have fresh air to breathe. The fumes of dye and bleach could make you faint or become nauseous in the beginning of pregnancy, especially if your blood pressure is low.

Hot baths are harmful.

True. They’re risky, and hot tubs or whirlpools can double your chance of miscarriage, as a late 1990s study found. Also avoid saunas. But steamy showers are fine and warm baths might be OK, though if you’re prone to yeast or bacterial infections, a bath might further irritate that body area. “Another concern for baths is women’s blood pressure can be low during early pregnancy, making them dizzy and raising risk for fainting,” she says. “Your Ob/Gyn can advise you on your personal risk.”

You can bank on your due date and deliver nine months to the day after conception.

False. Alas, pregnancy typically lasts 40 weeks, technically just over nine months. “Nine months, or 36 weeks, is considered a preterm birth,” says Dr. England.

Don't swim in public pools.

True. You cannot drown your baby since water cannot enter the amniotic sac. But germs can, so you could pick up a harmful infection. “Some kiddos urinate in community pools,” Dr. England says. “If your friend has a pool, it’s easier to assess whether it’s safe.”

Walking or spicy foods will induce labor.

False. Walking, intercourse or spicy foods won’t bring on baby or shorten labor. The drugs pitocin, cervidil and misoprostol, however, will. So can a cervical balloon catheter.

“Even then, it might take one to two days to reach active labor,” she says. “I always counsel patients that this is a marathon, not a sprint. You cannot snap your fingers and have a baby right away.”

Cat litter causes birth defects.

True. It can, since the parasite toxoplasmosis sometimes found in feline feces could be transmitted to your fetus. Your baby could be stillborn, grow poorly in the womb or have excess fluid collect in the brain, known as hydrocephalus. Epilepsy, blindness, cerebral palsy or too-small brains are dangers from contamination. “You don’t need to give away your cat. Instead ask someone else to change the litter box,” she says. Consider that a pregnancy perk.

It's dangerous to exercise.

False. Other than hot yoga, working out helps mom and baby during pregnancy, especially if you exercised before. Check with your doctor, if you’re concerned about miscarriage or preterm birth.

“We caution against hot yoga because you might faint,” says Dr. England.

New exercisers can safely walk briskly 30 minutes daily. If Texas’ torrid temps make you uncomfortable, walk on a treadmill or at a mall.

Yo never should sleep on your back.

True. “Doctors recommend against sleeping on your back during the second and third trimester because the entire weight of the baby presses on your back and the vena cava, the main blood vessel that returns blood to your heart from the lower body. This may cut blood flow to the baby, and along with it oxygen and nutrients.

That does you no favors either by aggravating backaches, hemorrhoids, dizziness and ankle/feet swelling. “That’s why we recommend sleeping on your side–if possible the left side. That increases blood flow to the baby,” says Dr. England.

If you wake up on your back, don’t panic, just switch to your side.

You cannot get pregnant while nursing.

False. If you breastfeed, you may have no periods, but you still can ovulate. Your age, frequency and length of nursing can lead to infertility—but there’s no guarantee.

“The basis for lactation infertility is not completely understood. However the hormone prolactin may play a role when elevated with breastfeeding,” Dr. England says. “We recommend women who want to delay subsequent pregnancy use contraception. Lactation alone is unreliable in preventing pregnancy.”

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