Old wives’ tales gender predictions like carrying low, a fast heart rate or the Chinese calendar are fun to try, but studies show none can reliably tell you whether you are having a boy or a girl.
Carrying high? Craving sweets? Ring swinging in circles? Old wives’ tales gender guesses are part of almost every pregnancy, and half the fun is that everyone has an opinion.
Below are 20 of the most common boy or girl tales, what each one claims, and what the research says. We also cover the one tale you should never try, and the real tests that can tell you your baby’s sex.
Key Takeaways
No old wives’ tale reliably predicts your baby’s sex; each is right about half the time by chance.
A 2023 meta-analysis found no significant first-trimester heart rate difference between boys and girls.
The Chinese gender calendar was right about 50% of the time in 2.8 million Swedish births.
Never do the drain cleaner test: drain cleaner can cause chemical burns.
Cell-free DNA screening (from about 10 weeks) and the ultrasound around 20 weeks can show the sex.
Table of Contents
Old Wives’ Tales Gender Predictions: The Short Answer
Quick Answer
Old wives’ tales gender predictions are fun, but none of them can tell you your baby’s sex. Researchers have tested a few: a 2023 meta-analysis found no significant difference in first-trimester heart rate between boys and girls, and a study of 2.8 million Swedish births found the Chinese gender calendar was right about 50% of the time, the same as a coin toss. The reliable ways to learn the sex are cell-free DNA screening (from about 10 weeks) and the mid-pregnancy ultrasound (around 20 weeks).
Every tale below has roughly a 50/50 chance of being right, simply because there are two common outcomes. That is exactly why they feel so convincing: everyone knows someone whose bump, cravings or ring test “called it.” They work as conversation starters and party games, not as predictions.
Why the Tales Seem to Work
Any tale is right about half the time by chance, and the hits get retold while the misses are forgotten. Researchers from the University of Michigan and Sweden’s Karolinska Institute put it bluntly about the Chinese calendar: it is no better at predicting a baby’s sex than tossing a coin.
Many body changes the tales point to are real; they just are not linked to sex. As Cleveland Clinic ob/gyn Catherine Caponero, DO, puts it: “There are no physical changes during pregnancy that will indicate the sex of the baby.”
20 Old Wives’ Tales for Boy or Girl: The Full Table
Versions of these tales vary from family to family, and some even flip boy and girl. Here are the 20 most common ones, what they claim, and what the evidence says.
#
Tale
Says boy
Says girl
What the evidence says
1
Carrying high or low
Carrying low
Carrying high
A Cleveland Clinic ob/gyn says there is no science behind it
2
Bump shape
Narrow bump that sticks out
Wide, round bump
No evidence; a Cleveland Clinic ob/gyn says no physical changes in pregnancy indicate the baby’s sex
3
Heart rate
Below 140 bpm
Above 140 bpm
2023 meta-analysis: no significant difference in first-trimester heart rate by sex
4
Cravings
Salty or savory
Sweet
We found no study supporting it
5
Morning sickness
Little or none
Severe
Ordinary nausea: no science behind it. Severe hyperemesis is modestly linked to girls (see below)
6
Heartburn
Little or none
Constant or intense
We found no study supporting it
7
Linea nigra
Line runs above the belly button
Line stops below it
No evidence; a Cleveland Clinic ob/gyn says no physical changes in pregnancy indicate the baby’s sex
8
Skin
Clear skin or a glow
Oily skin and acne
Hormones raise oil production in any pregnancy; no link to sex
9
Hair and nails
Shiny and healthy
Dry, thin or brittle
Hormone-driven changes happen in any pregnancy; no link to sex
10
Swollen feet
Swollen feet
No swelling
No evidence; a Cleveland Clinic ob/gyn says no physical changes in pregnancy indicate the baby’s sex
11
Breast size
Very large and heavy
Fuller but in proportion
No evidence; a Cleveland Clinic ob/gyn says no physical changes in pregnancy indicate the baby’s sex
12
Urine color
Bright
Dark or normal yellow
No evidence; a Cleveland Clinic ob/gyn says no physical changes in pregnancy indicate the baby’s sex
13
Clumsiness or pregnancy brain
Tired and clumsy
Alert and steady
We found no study supporting it
14
Sleeping side
Fall asleep on your left
Fall asleep on your right
We found no study supporting it
15
Partner’s weight gain
Partner’s weight stays the same
Partner gains weight
We found no study supporting it
16
Chinese gender calendar
Chart shows boy
Chart shows girl
2.8 million Swedish births: about 50% correct, a coin toss
17
Mayan method
Your age at conception and the year are one odd, one even
Both odd or both even
We found no study supporting it
18
Ring or pendulum test
Swings side to side
Swings in a circle
We found no study supporting it
19
Baking soda test
Urine fizzes
Stays flat
We found no study supporting it
20
Drain cleaner (Drano) test
Turns one color
Turns another
DANGEROUS: drain cleaner can cause chemical burns. Never do it
The 20 old wives’ tales gender predictions covered in this guide.
Body Tales: Carrying, Bump Shape, Skin and Hair
Carrying high or low, and bump shape. Cleveland Clinic ob/gyn Justin Lappen, MD, lists “You’re carrying low, so it must be a boy” among the sayings with no science to back them up. For what is typical, see when do you start showing.
Skin, glow and acne. One version says a glow means a boy and acne means a girl. Dr. Caponero explains that a surge in hormones can make skin produce more oil, which can look shiny or cause breakouts, and that higher blood volume can bring rosy cheeks. These happen in pregnancies of either sex, and Cleveland Clinic calls the method unreliable.
Hair and nails. Cleveland Clinic notes hair may grow longer and thicker during pregnancy because of hormones, and nails may grow faster and stronger, or turn softer and more brittle. Again, nothing ties these to a boy or a girl.
Linea nigra, feet, breasts and urine. We found no research linking where the dark belly line starts, swollen feet, breast size or urine color to fetal sex. If any swelling is sudden or severe, call your provider rather than reading it as a clue. Our second trimester and third trimester guides cover what is normal.
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Symptom Tales: Heart Rate, Morning Sickness, Cravings and Heartburn
The 140 bpm heart rate rule. According to Cleveland Clinic, an average fetal heart rate ranges from 110 to 160 beats per minute and changes when the baby is active. A 2023 systematic review and meta-analysis in BMC Pregnancy and Childbirth pooled five studies and found no significant difference in mean first-trimester heart rate between male and female fetuses. The authors concluded that heart rate is not a reliable predictor of fetal sex, and noted that male fetuses actually ran very slightly faster, the opposite of the tale, though the difference was minimal.
Morning sickness. Ordinary nausea is the tale Dr. Lappen calls unsupported. There is one real, small signal at the extreme end: a 2011 systematic review and meta-analysis in BJOG found that women with hyperemesis gravidarum, a severe form of pregnancy nausea and vomiting, were more likely to have a girl (odds ratio 1.27). That modest group link cannot predict one pregnancy. If you cannot keep fluids down, call your provider; our first trimester guide covers early symptoms.
Cravings and heartburn. Sweet means girl, salty means boy; heartburn means a girl (or, in another version, a baby with lots of hair). We found no study supporting the cravings or heartburn sex predictions.
Clumsiness, sleeping side and partner weight gain. Folklore, with no research behind them.
The Chinese Gender Calendar: How Accurate Is It?
The Chinese gender calendar (or lunar calendar) uses the pregnant person’s lunar age and the month of conception to “predict” boy or girl. The University of Michigan notes some websites claim up to 93% accuracy.
Researchers tested it on real data. A study led by Eduardo Villamor of the University of Michigan School of Public Health, with colleagues at Sweden’s Karolinska Institute, applied the calendar to 2.8 million Swedish births from 1973 to 2006. It predicted the sex correctly about 50% of the time, the same as flipping a coin. The Mayan odd-and-even method is arithmetic, not biology, too.
Kitchen Tests: Ring, Baking Soda and the Dangerous Drano Test
Ring or pendulum test. A ring on a string or a needle and thread is dangled over your belly or wrist: side to side means boy, circles mean girl. It is harmless party fun, but we found no study supporting it.
Baking soda test. Urine fizzes in baking soda for a boy, stays flat for a girl. We found no study supporting it either.
Never do the drain cleaner (Drano) test. This “test” mixes urine with drain cleaner and reads the color. It is dangerous and has nothing to do with your baby’s sex. Poison Control explains that many drain cleaners contain strong acids (sulfuric or hydrochloric acid) or strong alkalis (sodium or potassium hydroxide) that can cause pain, irritation and burns on contact with skin, that drain cleaner can splash back, and that some products generate heat when mixed. Its first-aid guidance covers swallowing it, skin contact and breathing in fumes.
If anyone swallows drain cleaner, gets it on their skin or breathes in fumes, contact Poison Control right away at 1-800-222-1222 or use webPOISONCONTROL online.
If someone has trouble breathing, collapses or will not wake up, call 911.
Ultrasound Theories You Will See Online
Two internet theories try to read the sex from early ultrasound images: the Ramzi method (which side of the uterus the baby or placenta seems to be on) and the nub theory (the angle of the developing genital area on an early scan). We could not find a validated study we could read for either. Dr. Lappen notes that before about 16 weeks, an ultrasound is not a reliable way to determine sex at all, so treat early-scan guesses as one more fun tale.
How You Can Actually Find Out Your Baby’s Sex
Test
When
What it is
Notes
Cell-free DNA screening (NIPT)
As early as 10 weeks (MedlinePlus)
A blood test from the pregnant person that screens for certain chromosome conditions and can also reveal sex
A screening test, not a diagnosis; Dr. Lappen says doctors do not typically use it only as an early sex reveal
Mid-pregnancy ultrasound
Usually around 20 weeks (Cleveland Clinic)
The detailed scan of the baby’s body; genitals can usually be identified
Depends on the baby’s position; before about 16 weeks, ultrasound is not reliable for sex
Chorionic villus sampling (CVS)
Weeks 10 to 13 (MedlinePlus); usually 11 to 13 (Cleveland Clinic)
Diagnostic test of placental cells
Small risk of miscarriage; not done just to learn sex
Amniocentesis
Usually weeks 15 to 20 (MedlinePlus)
Diagnostic test of amniotic fluid
Small risk of miscarriage or infection; not done just to learn sex
Medical ways to learn your baby’s sex, with timing per the sources listed.
CVS and amniocentesis are offered for medical reasons, such as a screening result that needs confirming. MedlinePlus describes them as usually very safe but with a slight risk of miscarriage, and Cleveland Clinic says they should not be used just to find out the sex. If you want to know, ask your provider which tests are part of your care.
Make It a Game: Score Your Tales
Old wives’ tales are best as a game. Before your scan or reveal, mark each tale in the table boy or girl and tally the score. Have friends and family do the same, then see who called it after the reveal.
Print or copy the 20 tales onto a card for each guest (skip the drain cleaner test; just list it as the one nobody tries).
Give a point for each tale that matches the real result.
Old wives’ tales gender predictions are a sweet tradition and a great icebreaker, but the evidence is clear on the ones researchers have tested: heart rate and the Chinese calendar do no better than chance, and the rest have nothing behind them. Enjoy the guessing, skip the drain cleaner, and leave the real answer to cell-free DNA screening or your mid-pregnancy ultrasound if you want to know before birth.
No. Each tale has about a 50/50 chance of being right simply because there are two common outcomes. When researchers tested the Chinese gender calendar on 2.8 million Swedish births, it was right about half the time, and a 2023 meta-analysis found first-trimester heart rate does not reliably predict sex.
Does a fast heartbeat mean it is a girl?
No. Cleveland Clinic says an average fetal heart rate ranges from 110 to 160 beats per minute and that heart rate does not predict sex. A 2023 meta-analysis of five studies found no significant difference between male and female fetuses in the first trimester, with boys very slightly faster, the opposite of the tale.
How accurate is the Chinese gender calendar?
Not accurate. A study led by University of Michigan and Karolinska Institute researchers applied the calendar to 2.8 million Swedish births from 1973 to 2006 and found it predicted the sex correctly about 50% of the time. That is the same as flipping a coin, despite websites claiming up to 93%.
Does bad morning sickness mean you are having a girl?
Not for ordinary nausea. A Cleveland Clinic ob/gyn says there is no science behind it. A 2011 meta-analysis did find that women with hyperemesis gravidarum, a severe form of pregnancy sickness, were somewhat more likely to have a girl, but that modest group link cannot predict the sex of one pregnancy.
What are the signs you are having a boy?
There are no reliable physical signs. Tales say carrying low, a narrow bump, salty cravings or a slower heart rate mean a boy, but a Cleveland Clinic ob/gyn says no physical changes during pregnancy indicate the baby’s sex. Cell-free DNA screening or the mid-pregnancy ultrasound are the reliable ways to find out.
When can you find out the baby’s sex?
Cell-free DNA screening, a blood test, can be done as early as 10 weeks and can reveal sex. The mid-pregnancy ultrasound, usually around 20 weeks, can often show it too, depending on the baby’s position. CVS and amniocentesis also show sex but carry a small miscarriage risk and are not done just for that.
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Nouri S, Kalantar MH, Safi F, Almasi-Hashiani A. The role of fetal heart rate in first trimester sonograms in prediction of fetal sex: a systematic review and meta-analysis. BMC Pregnancy Childbirth. 2023;23:582. https://pubmed.ncbi.nlm.nih.gov/37573392/
Consequences of hyperemesis gravidarum for offspring: a systematic review and meta-analysis. BJOG. 2011;118(11):1302-1313. https://pubmed.ncbi.nlm.nih.gov/21749625/
