Pregnancy myths, fact-checked

Pregnancy attracts folklore like nothing else in medicine — some of it charming, some of it anxiety-inducing, most of it delivered with total confidence by someone at a barbecue. Here’s a fact-check of the classics, so you can nod politely and know better.

“You’re eating for two.” The most persistent one, and the wrongest. Energy needs barely change in the first trimester and rise only modestly later — the equivalent of an extra snack or light meal a day, not a second dinner. The “two” you’re eating for weighs less than a chihuahua. Eat to genuine hunger, aim for quality over quantity, and ignore anyone loading your plate “for the baby”.

“Carrying low means a boy; heartburn means a hairy baby; craving sweets means a girl.” Bump shape reflects your muscles, torso length and the baby’s position — not sex. Cravings reflect hormones and whimsy. The 140-beats heart rate rule performs at coin-flip accuracy. (Delightful exception: the heartburn– hair link was actually studied, and a small study found a loose association — hormones that relax your oesophagus may also influence fetal hair. File under “folklore’s one lucky win”, not prediction science.) The only reliable pre-birth sex checks are chromosomes and ultrasound.

“Don’t raise your arms above your head — the cord will wrap.” Complete anatomy fiction: your arms connect to your shoulders, not your uterus, and cord position depends on the baby’s own acrobatics. Hang the washing freely. Nuchal cords (cord around the neck) occur in about a fifth of births regardless and are usually a non-event the midwife handles without you ever knowing.

“No exercise — you’ll shake the baby loose.” The baby is suspended in a fluid shock-absorber inside a muscular fortress; a jog does not register. The evidence runs entirely the other way — exercise in a normal pregnancy means better sleep, less back pain, lower gestational diabetes risk and often easier labour. The real rules are about overheating, contact risks and listening to your body, not about stillness. (Same verdict for sex: amniotic sac plus cervix plug equals baby entirely undisturbed, whatever your partner worries.)

“You can’t dye your hair / have coffee / eat any seafood.” Softened versions of real guidance, hardened into bans. Hair dye’s absorption is minimal — ventilation and patch tests are the sensible bit. Caffeine is fine in moderation (the standard guidance allows a coffee or two a day). Fish is actively encouraged — it’s specific high-mercury species and raw preparations that are limited, and the seafood article has the actual list. The pattern to notice: pregnancy advice usually says less or differently, and the barbecue version rounds it to never.

“Morning sickness means a girl / no sickness means something’s wrong.” Nausea tracks hormones and luck, not sex (there’s a barely-detectable statistical lean that’s useless for prediction), and plenty of textbook pregnancies feature no sickness at all. Symptom intensity is not a wellness meter — the scan is.

“Babies come at nine months, and second labours are always fast.” A due date is the midpoint of a five-week normal window (37 to 42 weeks); only about one in twenty babies arrives on it. Second labours are usually shorter — it’s a tendency, not a promise, so keep the hospital bag by the door either way.

“You’ll have to get rid of the cat.” The kernel: toxoplasmosis, a parasite sometimes carried in cat faeces, is genuinely worth avoiding in pregnancy. The actual guidance: keep the cat, delegate the litter tray (or wear gloves and wash up thoroughly), and know that gardening without gloves and undercooked meat are bigger toxoplasmosis routes than the average indoor cat, which likely doesn’t carry it at all. Rehoming is folklore’s overreaction to a litter-tray protocol.

“Flying causes miscarriage / the scanner hurts the baby.” Commercial flying in a normal pregnancy is safe — cabin pressure and security scanners do nothing to a fetus, and the airline cut-offs near your due date exist because airlines fear onboard births, not because flying is dangerous. The real in-flight advice is about you: move regularly and hydrate (pregnancy raises clot risk on long sits), and check your travel insurance covers pregnancy. The flying article has the details.

“Your bump is so small/big — is the baby okay?” Bump size is mostly torso length, muscle tone, baby’s position and how you carry — it correlates remarkably poorly with baby’s size, which is why midwives measure with a tape and scans rather than by eye. Bump commentary is a national sport with no predictive value; let it bounce off.

“A full moon / spicy food / that big walk will start labour.” Maternity wards have checked the moon thing repeatedly — no effect (nurses believe it anyway; solidarity). Spice, pineapple and bumpy roads mostly start heartburn. The folk methods with any evidence behind them are nipple stimulation (releases real oxytocin — discuss with your midwife before deploying) and possibly dates (the fruit, modest studies). Everything else is a placebo with good marketing — and babies come when they come.

Notice the common thread: myths thrive where anxiety meets uncertainty, and they’re usually either outdated caution or pattern-hunting on randomness. A good filter for the next confident barbecue claim: would my midwife say this? If you’re not sure — genuinely ask them; debunking folklore is one of their quiet professional pleasures, and no question is too silly to bring to an appointment.