Some parents want to learn their baby’s sex ASAP. Others opt for surprise, choosing to wait until their baby’s arrival to find out if they’re welcoming a son or a daughter.

If you fall into the former camp, you’ll likely look forward to your 18- to 20-week ultrasound, the routine second trimester ultrasound when your OB/GYN is generally able to determine the baby’s sex. Other parents find out a little sooner through noninvasive prenatal testing (NIPT), which can be done after week 9.

Of course, you may also be itching for information much earlier in your pregnancy, which is why the “ring gender test” — a superstitious method that has been passed down from generation to generation — sounds so intriguing.

What is the ring gender test?

The ring gender test is an old wives’ tale that claims to determine the sex of a pregnant woman’s baby. According to the believers in this test, the way a ring that’s attached to a piece of string moves when held over a mom-to-be’s belly can indicate whether the baby she’s carrying is a boy or a girl.

The ring test says I will have two girls and a boy; I currently have two girls, and we are hoping for a boy for our third.

What to Expect Community Member

“My husband’s family is Mexican and they fully believe in this,” What to Expect Community member Alexandriakrr says. “It was correct with my first, a girl. This time it says a boy. I’m only 9 weeks, so I don’t know yet. But it is 50/50 odds!”

How to do the ring gender test

If you want to try the ring gender test, all you need is a piece of thread attached to a ring (traditionally the expectant mom’s wedding band) and another person to hold the thread for you.

• Lie on your back and have another person dangle the thread over your baby bump, allowing it to move in whatever motion comes organically.
• If the ring moves back and forth like a pendulum: the baby is a boy.
• If the ring moves in a circle: the baby is a girl.

Does the ring gender test really work?

Some moms in the What to Expect Community believe the ring gender test works. 

“I tried the ring test three separate times,” Calimom1987 wrote. “It says I’m going to have two girls and a boy. I currently have two girls, and we are hoping for a boy for our third.”

“I do this same method, and it has been the same every single time: girl, boy, boy, girl,” SoDakMama2015 added. “It has always been accurate and the same for my sister as well.”

Although some expectant parents swear the ring gender test can provide on-point results, this is another gender prediction superstition that’s just for fun and doesn’t have the science to back it up.

Johns Hopkins Bloomberg School of Public Health actually did include the gender ring test in a 1999 study. Researchers asked 104 pregnant women to use any method they liked (“folk adages, dreams, hunches,” including the ring gender test) to guess the sex of their babies. The result: Moms guessed correctly 55% of the time, which the study pointed out is “a rate no better than mere guesswork could provide.”

Better alternatives to the ring gender test

If you want to know your baby’s sex prior to your second trimester ultrasound, there are several sex-prediction testing options. Over-the-counter gender prediction kits claim to have an accuracy rate of anywhere from 80 to 90%, but they cost anywhere from $40 for a urine-based test to a few hundred for a blood-sample test and often raise more questions than answers.

There are two other testing options that are more formal and high-tech:

Noninvasive prenatal testing (NIPT)

As early as 9 weeks into your pregnancy, you can learn the sex of your baby through a simple blood test. Noninvasive prenatal testing (NIPT) is more than 99% accurate at predicting a baby’s sex, plus it offers a rundown of a baby’s risk of certain chromosomal abnormalities including trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome). 

It’s suggested for moms whose age or genetic history indicates there might be a risk of birth defects, and it’s not invasive — meaning there’s no risk for you or your baby. If you’re interested in having NIPT to find out your baby’s risk of chromosomal abnormalities in addition to finding out his or her gender, talk to your doctor.

Chorionic villus sampling (CVS) and amniocentesis 

Both chorionic villus sampling (CVS) and amniocentesis are invasive diagnostic tests that analyze a baby’s genetic makeup and screen for chromosomal abnormalities (between week 10 and 13 of pregnancy for CVS and typically between week 16 and 18 for amnio, though it can vary). 

Again, these tests are usually recommended for moms who are at a higher risk for complications, especially since they’re invasive (which slightly elevates your risk of miscarriage). In other words, they’re not designed for parents who are just curious about their baby’s sex. But if your practitioner recommends you have one or the other (and you’re itching to find out the sex of your baby-to-be), the results can tell you the baby’s gender with 100% accuracy.

The bottom line: There’s no harm in doing the ring gender test. After all, plenty of moms are drawn to it, if only for the entertainment value. But for a more accurate answer, wait for the results of your NIPT test, 20-week ultrasound, or CVS or amniocentesis test.