Boy or Girl? Old Wives' Tales and What the Studies Found

Do old wives' tales predict boy or girl?

Not in any test so far. When researchers have checked the popular signs against babies' actual sex, they have come out at or close to chance — for a question with two possible answers, about as often right as a tossed coin.

Guessing is part of the fun for many families, and nothing here is meant to spoil it. Below is what each tale claims and what happened when someone measured it; where nobody has, we say so.

Carrying high or low

The tale: a bump that sits low or sticks straight out in front means a boy; one that sits high or spreads around your middle means a girl.

Researchers at Johns Hopkins asked 104 pregnant women who did not know their baby's sex what they predicted and why, then checked. Fetal sex "was not systematically related to the shape of the woman's abdomen", and women who based their guess on how they were carrying did worse than those who went on dreams or feelings. For what does shape a bump, see when you start showing.

The heart rate rule

The tale: over 140 beats per minute means a girl, under 140 a boy. One research team summarised the folklore as "the 120–140 bpm range for boys and the 140–160 bpm range for girls".

It has been tested more than any other tale, and it fails. A 2023 systematic review pooled five first-trimester studies, found no significant difference between boys' and girls' average heart rates, and concluded that heart rate "is not a reliable predictive test for fetal sex determination". The detail is on our page on the heart rate gender myth.

Does bad morning sickness mean a girl?

For ordinary morning sickness, no. In the Johns Hopkins study, the baby's sex was not systematically related to how common morning sickness was.

Severe sickness is where the folklore has a grain of truth. A Washington State study compared 2,110 women admitted to hospital with hyperemesis gravidarum in the first trimester with 9,783 women who were not. Those admitted had 50% higher odds of having a girl (odds ratio 1.5), rising to 1.8 for stays of three days or more. That is a tilt across thousands of pregnancies, not a test for yours.

If sickness is stopping you keeping food or drink down, our page on hyperemesis gravidarum sets out when to call. For the ordinary kind, see what actually helps morning sickness.

Cravings: sweet for a girl, salty for a boy

We could not find any study that has tested cravings against the baby's sex. The study usually quoted measured something else: how much women ate. In Boston, food questionnaires from 244 women in the second trimester showed those carrying boys ate more energy each day — 9.6% more after adjustment — across protein, carbohydrate and fat alike, a difference the authors called "marginally significant". It says nothing about sweet versus salty. For cravings themselves, including for non-food items, see pregnancy cravings.

The Chinese calendar

The chart, which crosses the mother's lunar age with the lunar month of conception, was tested against 2,840,755 singleton births in Sweden from 1973 to 2006. Agreement with the real result was a kappa of 0.0002 — effectively zero — and no better in any subgroup the researchers checked. The researchers concluded it "is no better at predicting the sex of a baby than tossing a coin". Our Chinese gender predictor does the lunar arithmetic properly and is honest about the odds.

Mother's intuition and dreams

A clinic in Wisconsin asked 1,026 women at their 17 to 23 week scan whether they had a feeling about the sex. The 411 who did were right 51% of the time. The 53 with a strong intuition reached 62%, but that difference was not statistically significant. The authors' conclusion: intuition "is no better at accurately predicting fetal gender than flipping a coin".

The Johns Hopkins study was kinder to feelings: women who went on dreams or feelings were more likely to be right than those who went on bump shape, and women with more than twelve years of education guessed correctly 71% of the time. It was a small group, the researchers could not explain it, and their overall verdict was that "women were not good predictors of fetal sex".

The ring test, skin, hair and the linea nigra

The tales: a wedding ring on a thread swings in a circle over your bump for a girl and back and forth for a boy; breakouts mean a girl "stealing your beauty"; a dark line running up past your belly button means a boy; urine that fizzes with baking soda means a boy.

We searched PubMed and Europe PMC and found no study testing any of these. The nearest thing to data is an anecdote the Wisconsin team recorded: one husband performed the ring test 40 times, it said girl every time, and the baby was a boy. The skin changes themselves are explained on our page on skin changes in pregnancy.

Why do the tales seem to work? Because any guess at a two-way question is right about half the time, and the hits get retold.

What actually tells you the sex

• The mid-pregnancy scan. In England, the NHS offers the 20-week screening scan between 18 and 21 weeks. Its job is to check for 11 conditions, but the NHS says "you may be asked if you'd like to know the sex of your baby".
• A blood test for the baby's DNA. A JAMA meta-analysis of 57 studies found tests on the mother's blood detected a boy with 95.4% sensitivity and 98.6% specificity overall. Tests before 7 weeks, and tests on urine, were unreliable. Whether a screening test reports sex depends on where and why it is done: see NIPT and what it can tell you.
• The 12-week scan, sometimes. Judging the angle of the "nub" is nub theory, the only early-scan method with studies behind it: right most of the time by 13 weeks in trained hands, much less often at 11. Ramzi theory and skull theory have no studies.

Our guide to when you can find out the sex covers each option in full.

Frequently asked questions

Are old wives' tales for boy or girl accurate?

No. Every tale that has been tested — bump shape, heart rate, ordinary morning sickness, the Chinese calendar and mothers' intuition — came out at or near chance. The rest, including the ring test and skin or hair changes, have never been studied. Enjoy them as a game, and use a scan or blood test for an answer.

What are the signs you're having a boy in the first trimester?

There are no reliable ones. Carrying low, mild sickness, salty cravings and a slower heart rate are all folklore, and the ones that have been studied do not predict sex. From around 12 to 13 weeks, a trained sonographer may be able to judge it on the scan, though accuracy is much lower at 11 weeks.

Which old wives' tale is the most accurate?

None works as a test. The only sign with a real link is sickness severe enough for a hospital admission, which one large US study found carried 50% higher odds of a girl. That is a tilt across thousands of pregnancies, not an answer for yours, and every other tested tale came out at or near chance.