10 Pregnancy Myths Your Family Still Believes (But Science Says No)
Your aunt means well. Your mother-in-law definitely means well. But that doesn't mean they're right.
There’s something about pregnancy that turns everyone around you into an expert. The moment your bump becomes visible, the advice starts pouring in — from your grandmother, your coworker, the stranger in the grocery store who just wants to touch your belly. Most of it is well-intentioned. Some of it is sweet. And a surprising amount of it is completely, scientifically wrong.
Pregnancy myths have been passed down for generations, repeated so often that they feel like facts. The problem is that some of them cause real anxiety, unnecessary restrictions, or — in rarer cases — actual harm. It’s time to lay the most stubborn ones to rest, once and for all.
Here are 10 pregnancy myths that science has firmly debunked, explained clearly so you can smile politely at the next family gathering and know the truth.
Myth 1: “You’re Eating for Two”
The Myth: You’re growing a baby, so you need to eat twice as much. Go ahead, have the extra portion. Have two desserts. You’ve earned it.
What Science Actually Says:
This is probably the most widespread pregnancy myth in existence — and one that can genuinely affect your health if you take it literally.
In the first trimester, you need virtually zero additional calories beyond your normal intake. In the second trimester, most guidelines suggest an extra 300–350 calories per day. By the third trimester, that number rises to roughly 400–500 extra calories — the equivalent of a small snack, not a second meal.
The “eating for two” idea made more sense historically, when many pregnant women were undernourished and needed encouragement to eat more. Today, for most women in developed countries, excessive caloric intake during pregnancy is linked to excessive gestational weight gain, which raises the risk of gestational diabetes, preeclampsia, c-section delivery, and long-term weight retention.
You are nourishing for two. That’s very different from eating for two. Quality of food matters far more than quantity during pregnancy.
Tell your family: “The second person I’m eating for is the size of an avocado. She doesn’t need a second helping of pasta.”
Myth 2: “Don’t Raise Your Arms Above Your Head — It Will Wrap the Cord Around the Baby’s Neck”
The Myth: Reaching up high — hanging laundry, stretching, putting something on a shelf — can cause the umbilical cord to wrap around your baby’s neck and strangle them.
What Science Actually Says:
This myth is so widespread across so many cultures that it’s genuinely remarkable. Versions of it exist in Latin America, South Asia, East Asia, and across Europe. It is entirely false, and the logic behind it doesn’t hold up to even basic anatomy.
The umbilical cord floats in amniotic fluid, completely disconnected from your arms and their movements. What you do with your limbs on the outside of your body has zero physical effect on what the cord does inside your uterus. Cord nuchal wrapping (when the cord wraps around the baby’s neck) happens in approximately 20–30% of all deliveries, and it’s caused by the baby moving around inside the womb — not by anything the mother does with her arms.
Most babies born with a cord around their neck are born perfectly healthy. Trained birth attendants and obstetricians manage it routinely.
Raise your arms. Stretch. Hang your laundry. You are not putting your baby at risk.
Tell your family: “The cord is inside my uterus. My arms are outside my body. They are not connected.”
Myth 3: “Heartburn Means Your Baby Will Have Lots of Hair”
The Myth: If you’re suffering from terrible heartburn during pregnancy, it means your baby is going to be born with a full head of hair.
What Science Actually Says:
Here’s the thing — this one actually has a tiny grain of truth buried in it, which is partly why it has survived so long. A 2006 study published in Birth found a correlation between the severity of heartburn and the amount of neonatal hair. The proposed mechanism is that higher levels of estrogen and progesterone, which relax the esophageal sphincter and cause heartburn, also influence fetal hair growth.
But — and this is a big but — a correlation between two things caused by the same hormones is not the same as one causing the other. Heartburn does not cause hair. Hair does not cause heartburn. They’re both downstream effects of pregnancy hormones.
Plenty of women with severe heartburn deliver bald babies. Plenty of women with zero heartburn deliver babies with a thick dark mane. It’s a fun coincidence when it happens to line up, not a reliable prediction.
Heartburn is caused by your growing uterus pushing on your stomach and progesterone relaxing your lower esophageal sphincter. That’s it.
Tell your family: “The science is interesting, but I wouldn’t bet the nursery paint color on it.”
Myth 4: “You Can’t Exercise During Pregnancy — You Might Hurt the Baby”
The Myth: Pregnancy is a delicate state. You should rest, take it easy, and avoid anything strenuous. The baby could be harmed if you exert yourself.
What Science Actually Says:
This myth has caused generations of pregnant women to become unnecessarily sedentary — and the consequences for their health have been real.
The current consensus from major medical organizations, including the American College of Obstetricians and Gynecologists (ACOG), is that exercise during a healthy, uncomplicated pregnancy is not only safe but actively recommended. ACOG recommends at least 150 minutes of moderate-intensity aerobic activity per week throughout pregnancy for women without contraindications.
Regular exercise during pregnancy has been shown to reduce the risk of gestational diabetes, excessive weight gain, preeclampsia, preterm birth, cesarean delivery, postpartum depression, and back pain. It also improves sleep, mood, and energy levels throughout pregnancy.
Women who were runners before pregnancy can often continue running. Women who were swimmers can keep swimming. Even beginning a moderate exercise program during pregnancy — walking, prenatal yoga, low-impact aerobics — is beneficial.
There are some exceptions — women with certain conditions like placenta previa, incompetent cervix, or preterm labor risk may be advised to restrict activity. Always check with your provider. But for most healthy pregnant women, the couch is not the safe option. Movement is.
Tell your family: “My doctor actually told me to keep exercising. Inactivity is riskier for me right now.”
Myth 5: “You Shouldn’t Have Sex During Pregnancy — It Could Hurt the Baby”
The Myth: Sex during pregnancy is dangerous. The baby is right there. You could harm it, trigger labor, or cause a miscarriage.
What Science Actually Says:
For women with healthy, uncomplicated pregnancies, sex is completely safe throughout all three trimesters. The baby is protected by the amniotic sac, the amniotic fluid, the uterine wall, and the cervix — all of which serve as effective physical barriers. Nothing during intercourse reaches or impacts the baby.
Sex during pregnancy does not cause miscarriage in healthy pregnancies. Miscarriage in the first trimester is almost always caused by chromosomal abnormalities in the embryo — not by physical activity, sex, exercise, or anything the mother does.
Sex also does not trigger preterm labor in low-risk pregnancies. There is some evidence that prostaglandins in semen may have a mild cervical ripening effect at term, but this does not mean that sex causes premature birth in otherwise healthy pregnancies.
As with exercise, there are specific situations where a provider might recommend abstaining — placenta previa, unexplained bleeding, preterm labor risk, or ruptured membranes. Outside of those situations, intimacy is safe and many couples find it an important part of staying connected during pregnancy.
Tell your family: “The baby is behind several layers of protective fluid and tissue. We’re good, thanks.”
Myth 6: “A Big Belly Means a Big Baby — A Small Belly Means a Small Baby”
The Myth: You can tell how big a baby will be by the size and shape of the pregnant belly. Carrying “big” means a big baby. Carrying “small” means the baby might be dangerously small.
What Science Actually Says:
Belly size is one of the least reliable predictors of baby size, and the anxiety this myth causes pregnant women is completely unwarranted.
The size and shape of a pregnant belly is determined by a wide variety of factors: the mother’s pre-pregnancy body type and height, abdominal muscle tone, the position of the baby, the amount of amniotic fluid, whether it’s a first or subsequent pregnancy, and the position of the placenta. A tall woman with a long torso carries very differently from a petite woman, even if their babies are exactly the same size.
Babies who are genuinely measuring small or large for gestational age are identified through ultrasound measurements — not by looking at the mother’s belly from across the room. Your midwife or OB tracks fundal height (the measurement from the pubic bone to the top of the uterus) at every appointment, and if there’s a concern, an ultrasound provides far more reliable information.
Strangers commenting on the size of your belly — “you’re huge!”, “you’re so small, are you sure you’re eating enough?” — are making observations based on zero clinical information and an enormous amount of cultural mythology.
Tell your family: “That’s what ultrasounds are for. My measurements are perfectly on track, thank you.”
Myth 7: “You Can’t Eat Fish, Sushi, Deli Meat, or Soft Cheese — Any of It”
The Myth: Pregnancy means saying goodbye to an entire category of foods. Fish is dangerous. Sushi will make you sick. Deli meat will harm the baby. Soft cheese is off limits entirely.
What Science Actually Says:
Food rules during pregnancy are real and important — but the blanket bans that get repeated in family conversations are often exaggerated, outdated, or flat-out wrong.
Fish is actually one of the best things you can eat during pregnancy. Omega-3 fatty acids, particularly DHA, are critical for fetal brain and eye development. The FDA and EPA recommend that pregnant women eat 2–3 servings of low-mercury fish per week. The fish to genuinely avoid are high-mercury species: shark, swordfish, king mackerel, tilefish, and bigeye tuna. Salmon, sardines, shrimp, cod, tilapia, and canned light tuna are all safe and beneficial.
Sushi is more nuanced. Raw fish from high-quality, reputable establishments carries a small risk of listeria or parasites. Many OBs advise caution rather than total avoidance. Cooked sushi is entirely safe. The risk is real but small, and it varies significantly by restaurant quality.
Deli meat should be heated to steaming before eating, as cold cuts can harbor listeria. But a turkey sandwich that’s been heated is completely fine.
Soft cheeses made from pasteurized milk — which is the vast majority sold in the US and UK — are safe. The concern is specifically about unpasteurized (raw milk) soft cheeses, which are relatively rare. Check the label. “Pasteurized” on the label means it’s safe.
The blanket bans your family may have learned came from an era of less nuanced nutritional guidance. Current recommendations are more targeted and more evidence-based.
Tell your family: “The guidelines have actually been updated. I’ve talked to my doctor and I know what’s on my list.”
Myth 8: “The Shape of Your Belly Tells You the Baby’s Sex”
The Myth: Carrying high means it’s a girl. Carrying low means it’s a boy. Or is it the other way around? If the belly is round and out front, it’s one sex. If it spreads to the sides, it’s the other.
What Science Actually Says:
This one is harmless fun at baby showers, but it’s worth being clear: there is no scientific evidence that the shape or position of a pregnant belly predicts fetal sex. None.
The shape of your belly is determined by the same factors mentioned in Myth 6 — your body type, muscle tone, how the baby is positioned, amniotic fluid volume, and whether you’ve been pregnant before. None of these factors are influenced by whether the baby has XX or XY chromosomes.
Studies that have tested the belly shape prediction method have found it to be accurate roughly 50% of the time — which is exactly what you’d expect from a coin flip. The baby bump is a coin flip. The coin flip is not an ultrasound.
The same goes for other popular sex prediction methods: the ring test, the Chinese gender calendar, cravings for sweet vs. salty food, fetal heart rate, how much morning sickness you have, how your hair and skin look. All of them perform at or near chance levels in controlled studies.
If you want to know the sex of your baby, an anatomy scan ultrasound (usually around 18–20 weeks) or NIPT blood test is the way to go.
Tell your family: “It’s a 50/50 guess either way. We’ll find out at the ultrasound.”
Myth 9: “Stress During Pregnancy Will Damage the Baby’s Brain”
The Myth: If you experience stress, worry, anxiety, or emotional upset during pregnancy, you will permanently damage your child’s brain or temperament. You must stay calm and positive at all times.
What Science Actually Says:
This myth is particularly cruel, because it causes stressed pregnant women to become stressed about being stressed — which helps no one.
Here’s what the research actually shows. Mild to moderate, everyday stress — the kind that every human being experiences as part of normal life — has no proven harmful effect on a developing baby. Stress from a difficult conversation, a deadline at work, an argument with a partner, a scary news story — these are normal human experiences and do not harm your baby.
What the research does show is that chronic, severe, prolonged stress — the kind associated with ongoing trauma, intimate partner violence, poverty, or major life crisis — can have effects on pregnancy outcomes, including slightly elevated risks of preterm birth and low birth weight. The mechanism is thought to involve sustained elevated cortisol levels over long periods.
This is an important distinction. Occasional stress is normal and harmless. Severe, unrelenting distress over months is a genuine concern — not because you’re “damaging your baby’s brain,” but because it affects your overall health, sleep, immune function, and wellbeing.
If you’re experiencing significant anxiety or depression during pregnancy, please speak with your healthcare provider. Perinatal mental health is taken seriously by modern medicine, and support is available. But everyday worry and normal emotional responses to life events? That’s just being human.
Tell your family: “Telling a pregnant woman to never feel stressed is not helpful. I’m managing it, and I’m fine.”
Myth 10: “Once a C-Section, Always a C-Section”
The Myth: If you had a cesarean section for your first baby, you will have to have one for every subsequent pregnancy. There is no other option. A vaginal birth after a c-section is too dangerous to attempt.
What Science Actually Says:
This myth, while once closer to medical practice than the others on this list, no longer reflects current evidence-based obstetric care.
Vaginal birth after cesarean (VBAC) is a safe, viable option for many women. The American College of Obstetricians and Gynecologists has supported VBAC as an appropriate choice since the 1980s and has updated its guidelines repeatedly to reflect growing evidence of its safety.
The primary concern with VBAC is uterine rupture at the scar site, which occurs in approximately 0.5–0.9% of VBAC attempts — less than 1 in 100. In the right candidates, at the right facilities, the risk of VBAC is comparable to the risks of a repeat cesarean, which carries its own significant risks including blood loss, infection, longer recovery, and complications in future pregnancies.
Candidates for VBAC are evaluated based on the type of uterine incision from the previous cesarean (a low transverse incision is preferable), the reason for the previous cesarean, overall health, and the facilities available. Many women who want a VBAC are excellent candidates for one.
The “always a c-section” rule came from an era of different surgical techniques and less understanding of uterine scar integrity. The conversation has moved significantly since then. If you’ve had a cesarean and want to discuss VBAC for a future pregnancy, speak with a provider who is experienced in supporting it.
Tell your family: “My OB and I are making that decision together, based on my specific history and current guidelines.”
Why These Myths Persist — And Why It Matters
Pregnancy myths survive for a few reasons. Some contain a small seed of truth that got distorted over generations. Some filled a real knowledge gap before modern medicine existed. Some are comforting because they give people a sense of control — if you just follow these rules, everything will be fine.
But some of these myths cause real harm. They create unnecessary fear, restrict healthy behaviors, burden already-stressed pregnant women with impossible standards, and in some cases lead to worse health decisions.
The antidote isn’t rudeness to well-meaning family members. It’s information. Knowing the evidence behind these beliefs means you can gently correct them, protect your own peace of mind, and make decisions based on facts rather than fear.
Your pregnancy. Your body. Your choices — guided by actual science and actual healthcare providers who know your actual situation.
A Final Word to the Family Members Reading This
If someone shared this article with you, take it in the spirit it was intended. The people who love a pregnant woman most are often the ones most likely to pass along myths — because they care deeply and want to help. That impulse is beautiful.
But the best way to support a pregnant person is to trust them, trust their healthcare team, and offer love rather than unsolicited advice. Ask how they’re feeling. Bring them a meal. Tell them they’re doing an amazing job.
That’s the kind of support that actually helps.
