By Sarina Gomez
Most boy-or-girl old wives’ tales have been tested, and they fail: heart rate, the shape of your bump and the Chinese calendar do no better than a coin toss in published studies. One tale has a small grain of truth (very severe morning sickness is slightly more common with girls), and one is genuinely unsafe: the Drano test. Here is each tale, what it claims and what the research found.
The verdicts at a glance
Only one tale has any measurable link to the baby’s sex, and even that one can’t tell you anything about your own pregnancy. The table sums up the evidence; the sections below explain it.
| Tale | What it claims | What the evidence says | Verdict |
|---|---|---|---|
| Heart rate | Over 140 bpm means a girl | No real difference between boys and girls in the first trimester | Myth |
| Carrying high or low | Low and out front means a boy | Bump shape didn’t match the baby’s sex | Myth |
| Morning sickness | Bad nausea means a girl | Ordinary nausea: no link. Severe hyperemesis: a slight tilt toward girls | A small truth, useless as a test |
| Chinese calendar | Your age and conception month decide it | Tested on 2.8 million births: no better than chance | Myth |
| Cravings, ring test, skin, linea nigra | Sweet means girl, swinging ring, acne, a long dark line | Never tested in a published study | Pure folklore |
| Drano test | Urine plus drain cleaner changes color | No basis, and the fumes are hazardous | Skip it |
Heart rate over 140: the most-tested tale
A fast heartbeat doesn’t mean a girl. In a study of 477 pregnancies scanned before 14 weeks, girls averaged 151.7 beats per minute and boys 154.9, and the gap was not statistically significant (McKenna et al., Fetal Diagnosis and Therapy, 2006). If anything, the boys in that study ran a touch faster.
Heart rate changes a lot with gestational age and with what the baby is doing at that moment, so a single reading at an appointment says more about timing than sex. Our full breakdown of the research is in baby heart rate and gender.
Carrying high or low, and other bump-based tales
The shape of your bump tells you about your muscles, your build and the baby’s position, not the sex. Researchers at Johns Hopkins asked 104 pregnant women who didn’t know the sex how they thought they were carrying, then checked against the birth. Fetal sex “was not systematically related” to the shape of the abdomen, to morning sickness or to comparisons with earlier pregnancies (Perry, DiPietro and Costigan, Birth, 1999).
The same study turned up one odd finding. Mothers with more than 12 years of education guessed right 71% of the time, against 43% for less educated mothers, and guesses based on dreams or feelings beat guesses based on folklore. The authors couldn’t explain it, the sample was small, and they concluded that, in general, women were not good at guessing the sex. Treat it as a curiosity, not a method.
Morning sickness: the tale with a grain of truth
Ordinary nausea doesn’t point either way, but severe sickness leans slightly toward girls. The distinction matters:
- Everyday morning sickness showed no link to the baby’s sex in the Johns Hopkins study above.
- Hyperemesis gravidarum, the severe form that can lead to hospital care, is different. A Swedish registry study reported more girls among babies of mothers treated for it (Askling et al., The Lancet, 1999), and a later meta-analysis put the odds of a girl at about 1.27 times higher (Veenendaal et al., BJOG, 2011).
Higher odds across thousands of pregnancies is not a test for one. Plenty of mothers with severe sickness have boys. And if you can’t keep fluids down, that’s a reason to call your doctor or midwife, not a clue for the party.
The Chinese calendar: tested on 2.8 million births
The Chinese lunar calendar is no better than tossing a coin. Researchers applied the published chart to 2,840,755 Swedish births from 1973 to 2006, using the mother’s lunar age and month of conception. The agreement between the chart and the real sex was essentially zero, and it didn’t improve when they checked a subset with a website’s own lunar-date converter (Villamor et al., Paediatric and Perinatal Epidemiology, 2010). The authors advised against painting the nursery based on it.
If you still want to read the chart for fun, our guide to the Chinese gender chart shows how it works.
Cravings, the ring test and “girls steal your beauty”
These tales have simply never been studied. No peer-reviewed test of the craving rule (sweet for a girl, salty for a boy), the ring or pendulum swing, the length of the linea nigra, or the idea that a girl causes acne turns up in PubMed. That doesn’t make them true by default; it means nobody has found them worth testing.
They’re harmless as party games. The ring test, in particular, works well as a guest activity: everyone dangles a ring over the bump, writes down the swing, and you compare after the reveal. More ideas like that are in gender reveal games.
The Drano test: the one to skip
Don’t mix urine with drain cleaner. Many drain cleaners contain sodium hydroxide (lye), which MedlinePlus lists as a cause of poisoning by touch, swallowing or breathing it in, with symptoms that include breathing difficulty and throat swelling (MedlinePlus, sodium hydroxide poisoning). The color change you see says nothing about the baby, and different online “keys” don’t even agree on which color means what.
If anyone has been exposed, call the Poison Help line at 1-800-222-1222 in the US or your local emergency number. The baking soda version is not dangerous in the same way, but it has no evidence behind it either.
When a guess is just for fun, say so
Old wives’ tales are entertainment, and the healthiest way to enjoy them is to treat them that way. The same goes for apps. If you don’t know the sex yet, or you’re keeping it a surprise, the SeeMyBaby gender reveal party gives you a moment to share: you pull the ribbon on a gift box, and after you buy the gender add-on on the paywall, it opens on a drumroll with pink or blue balloons and confetti. What it shows is a playful AI guess, just for fun, not a medical result. If you already know the sex, you tell the app and no guess is made.
For a real answer, the options are medical. ACOG notes that a cell-free DNA blood screen can be done from 10 weeks and looks at the sex chromosomes (ACOG, prenatal genetic screening tests), and that at the standard 18–22 week ultrasound it may be possible to tell the sex if the baby is in a good position (ACOG, ultrasound exams). Our timeline of when you can find out the gender covers each one. For the early-scan theories, see nub theory and Ramzi and skull theory, and the wider question of whether any gender predictor is 100 percent accurate.
Sources
- McKenna DS et al. Gender-related differences in fetal heart rate during first trimester. Fetal Diagnosis and Therapy, 2006.
- Perry DF, DiPietro J, Costigan K. Are women carrying “basketballs” really having boys? Testing pregnancy folklore. Birth, 1999.
- Askling J et al. Sickness in pregnancy and sex of child. The Lancet, 1999.
- Veenendaal MV et al. Consequences of hyperemesis gravidarum for offspring: a systematic review and meta-analysis. BJOG, 2011.
- Villamor E et al. Accuracy of the Chinese lunar calendar method to predict a baby’s sex. Paediatric and Perinatal Epidemiology, 2010.
- MedlinePlus. Sodium hydroxide poisoning.
- ACOG. Prenatal genetic screening tests and Ultrasound exams.
More pregnancy and reveal guides are on the SeeMyBaby blog.
Questions parents ask
Is any old wives’ tale accurate for boy or girl?
None works as a test. The tested ones (heart rate, bump shape, everyday morning sickness, the Chinese calendar) perform at chance, and severe hyperemesis only shifts the odds slightly toward a girl.
Does carrying low mean a boy?
No. In a Johns Hopkins study of 104 women, the shape of the bump was not related to the baby’s sex. How you carry depends on your body, your muscle tone and the baby’s position.
Does a heart rate over 140 mean a girl?
No. In 477 first-trimester scans, girls averaged about 152 bpm and boys about 155 bpm, a difference too small to mean anything.
Is the Drano gender test safe?
No. Drain cleaners often contain sodium hydroxide, which can burn skin and irritate the airways, and the test has no basis. Call Poison Help at 1-800-222-1222 if anyone is exposed.
Is morning sickness worse with a girl?
Ordinary morning sickness shows no link. Severe hyperemesis gravidarum is slightly more common with girls across large groups, but many mothers with it have boys, so it can’t tell you about your own baby.
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