We’ve all heard the common rumors about pregnancy and labor— find out what’s fact and what’s fiction.

1. Labor starts when your water breaks.
It’s a familiar scene in movies: the woman’s water breaks and there’s a mad dash to the hospital. The reality however, is that it could take 24 (or more!) hours for labor to start.

“It means labor is on its way but it’s not necessarily going to put you into labor,” said Dr. Sheryl Ross, an OB/GYN at Providence Saint John’s Health Center in Santa Monica, Calif. What’s more, only about 10 percent of women will rupture their membranes before labor starts anyway.

If your water breaks but contractions haven’t started, it’s ok to stay home until they get stronger and closer together as long as the amniotic fluid is not green or bloody.

“It’s better to be patient because your body will kick into gear on its own,” Ross said.

2. You should eat for two.
You might think being pregnant is permission to increase your calories or to eat whatever you’re craving, but you only need an extra 300 calories— less than you need for breastfeeding, according to Jenna LoGiudice, a certified nurse midwife and assistant professor at Fairfield University’s School of Nursing.  

Plus, if your weight gain is above the guidelines for your body mass index (BMI), you’re at an increased risk for gestational diabetes, pregnancy complications and a more difficult delivery.

3. Sex isn’t fun during pregnancy.
Since blood volume increases almost 50 percent during pregnancy, more blood flow to the clitoris means stronger orgasms for you.

“Women can have even better sex than usual when they’re pregnant,”  LoGiudice said.  

4. Drinking coffee causes miscarriages.
If you can’t kick your Morning Joe habit, don’t sweat it. Less than 200 milligrams of caffeine has been shown to be safe during pregnancy. Pay attention to your daily consumption because caffeine in tea, soft drinks and chocolate can add up quickly.  

5. A glass of wine is ok.
A study earlier this year out of the University of Copenhagen found that children of women who drank in moderation during pregnancy fared better emotionally and behaviorally at 7-years-old compared to women who didn’t drink at all.

In fact years ago, alcohol was actually administered through an IV to help relax the uterus for women in preterm labor.

The American College of Obstetricians and Gynecologists (ACOG) says women should entirely abstain from alcohol during pregnancy. Some providers however, may decide to give the green light on a case-by-case basis but only after weighing the risks and benefits and giving guidelines about sensible amounts, Ross said.   

6. Eating fish in moderation will protect your baby from toxins.
A recent study published in the journal Environmental Health Perspectives found that fish advisories for pregnant women fail to cover persistent organic pollutants. Unlike mercury, these toxins can stay in the body for a long time.  It’s nearly impossible to figure out which types of fish are safe but at least be selective about where you purchase fish and how much you eat each week. Check the EPA’s website for guidelines on consuming fish.

7. If your baby is too big, you’ll need a cesarean.
If you’re full term and your baby is measuring 9 pounds or more, you have a higher chance of having a C-section. Plus, if you’ve been measuring large in previous weeks,  chances are your baby will be big too.

Yet consider this: Ultrasound has a 10 to 15 percent margin of error and it really depends on your body.

“Unless you know the shape and size of your pelvis, it does not matter how big your baby is,” LoGiudice said.

So a woman with a small frame might be able to birth a 10 pounder with no problem, while a larger woman may have trouble with a smaller baby.

“More often than not, that baby fits just fine for that woman,” she said.

8. You’ll poop when you push.
Sorry ladies, this is one of those realties not many women will admit happened to them. Yet eighty percent of pregnant women suffer from constipation, and the same muscles used for a bowel movement are the same you’ll use when you push. So if your poop is sitting there, it will get pushed out too. Breathe a sigh of relief and don’t be embarrassed if it happens because physicians are used to it.

“Embrace it, we don’t care,” Ross said.

9. Cocoa butter prevents stretch marks.
Slathering your belly in that expensive moisturizer won’t do anything to prevent stretch marks. And for some women, stretch marks are hereditary.

“If your skin is prone to stretch marks you’re going to get them,” LoGiudice said.  

The only thing that may help is to eat a diet rich in plenty of fruits and vegetables.

10. You should go into labor on or before your due date.  
Your due date is really only an estimate so don’t too worried about it.

“Most first-time moms actually go beyond their due date and less than 5 percent will actually have the baby on their due date,” LoGiudice said.

A good solution to alleviate stress? Avoid telling anyone your actual due date and give them a rough estimate (i.e., the middle of January) or a date two weeks after the estimated date.

11. Sex will kick start labor.  
It’s true that semen has prostaglandins, the same hormone used in cervical ripening agents used to thin out the cervix in the hospital. Yet “having sex doesn’t magically put you into labor, ” LoGiudice said.  “It helps to prepare for labor more than it does induce it.”

12. Pregnant women can’t get their hair dyed.
Most salons now use vegetable hair dyes and studies show getting your hair dyed or breathing in the fumes isn’t harmful to your baby. Nevertheless, make sure your salon is well-ventilated especially if you have morning sickness.

13. The way you carry determines your baby’s gender.
Guessing the baby’s gender based on how wide/pointy/low you’re carrying has been fodder for moms and strangers alike for years. Yet there’s no scientific evidence that any of it is true. So if you’ve chosen not to find out the gender or don’t want to spill the beans, simply smile and change the subject.

Julie Revelant is a health journalist and a consultant who provides content marketing and copywriting services for the healthcare industry. She's also a mom of two. Learn more about Julie at revelantwriting.com.