Predicting the Sex of Your Baby: Facts & Myths

How to Really Know if You’re Having a Girl or a Boy

Little boy looking at ultrasound scans of his pregnant mother
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After you see that positive pregnancy test result, your next question will likely be, “When am I due?” And your second thought is likely to be, “I wonder if I’ll have a girl or a boy.” Imagining the sex of your baby is a way to bond with your little one before they arrive. Friends and family (and even strangers) will likely be curious, too, often asking, “Do you know what you’re having?” And if you answer no, the follow-up is usually “Are you going to find out?”

Sometimes, knowing the sex of the unborn baby is desired for medical purposes. For example, when a specific genetic disease runs in the family and is gender specific. That said, most of the time, people wish to know out of pure curiosity. 

For those who do want to know, searching for answers (especially easy ones!) is common.

The Internet is full of myths and fairy tales about how to determine if you’re having a boy or a girl. Some “theories” appear to be quite scientific, but in reality lack any evidence. Of course, there are also medically sound ways to find out the sex of your baby while you’re pregnant, too.

Here’s everything you need to know about predicting the sex of your baby—the myths and the facts. 

Finding Out

Just over half of men and women want to find out the sex of their baby before the birth. One study found that 57 percent of couples wanted to find out.

Finding out if you’re having a boy or a girl before the baby arrives is a personal choice based on your circumstances and preference. While there is no right or wrong, there are pros and cons to either argument.

Here are some reasons why a parent might want to find out the sex ahead of time:

  • Hoping to bond earlier: The more you know about the baby, the closer you’ll feel before they arrive.
  • Pure curiosity: Not everyone likes surprises! You may just want to know.
  • Planning the nursery or baby clothes: Especially if you're partial to gender-specific themes or colors, you might want to plan this in advance.
  • Gender reveal party plans: Pretty popular these days, gender reveal parties sometimes are part of baby showers and allow you to share the news with loved ones. 
  • Strong preference for one sex or the other: For those whose desire to have either a boy or girl is strong, waiting to know until the birth may feel difficult. 
  • Medical decisions: In some cases, determining the sex of the baby is part of monitoring for congenital diseases that are more prevalent in boys or girls. However, it’s unusual in this case to only seek out the sex of the baby. More specific genetic testing is also likely to be done.

Alternatively, not every parent wants to know the sex of his or her baby before the birth. Or sometimes, one parent wants to know, but the other doesn’t. Here are some reasons why parents may wait to learn the sex:

  • To be surprised: For some, the desire to be surprised at the birth is stronger than the curiosity to find out sooner.  
  • Worried about gender disappointment: Gender disappointment is very real. (More on this below.) While some who have a strong preference may want to find out early, others may intentionally want to delay finding out. It’s harder to be disappointed about the sex of the baby on the day of the birth, due to all the other high, happy emotions at the event.
  • Not attached to sex-specific colors or stereotypes: Not everyone thinks boys should have blue nurseries and girls should have pink. Or, they may wish to encourage friends and family to go for more sex-neutral colors. Keeping the sex a secret makes that more likely. 
  • Religious or traditional beliefs: Some believe it is bad luck to find out the sex before the birth, or that it interferes with God’s plan. Some just have strong traditional customs and prefer to keep the sex a surprise until the baby is born.   

Possible Risks

While there’s no right or wrong answer to whether you should find out the sex of the baby before they’re born, there are some risks to consider.

Gender disappointment

When you desperately wanted a girl, and find out you’re having a boy, or vice versa, the result can be sadness, disappointment, and even grief.

Sometimes referred to as gender disappointment, many parents who are upset by the sex of their child keep their heartbreak quiet. They may feel ashamed of their reaction. Shouldn’t they just be happy with a healthy baby, they may think?

Every parent wants a healthy baby, but they also want a baby that fits certain ideas they have for success, like hoping their child will be of above average intelligence, handsome or beautiful, outgoing, or an above average decent human being. Along the same theme, some parents also hope for a boy or girl specifically. Every parent has dreams for their baby, even if they don’t voice them out loud.

When you find out the sex before the birth, and it’s not the answer you were hoping for, the feelings of disappointment may be stronger or harder to cope with when compared to learning the day of childbirth. They don’t get balanced out by the excitement of having a bouncing new baby. Still, it’s possible to experience gender disappointment even if you wait until the day of the birth to learn the sex of your child.

One possible advantage of finding out sooner rather than later is that if you know you will be distraught by news of one sex or the other, you can have time to seek professional counseling to work through your fears and emotions before the baby arrives. 

Sex misidentification

Mistakes are rare, but they do happen. One study found that in 1 out of 100 cases, the sex is misidentified during an ultrasound past 14 weeks. Other studies have found the occurrence for mistakes is even less than 1 percent of the time. If the genitals are malformed due to congenital anomalies, the odds for mistakes increase.

Ultrasounds during the first trimester—as opposed to during the second or third trimester—are much more likely to lead to mistaken sex identification.

Ultrasound technicians can successfully and accurately determine the sex of the baby only three out of four times during the first 12 weeks of pregnancy.

When it comes to non-scientific methods of determining sex, mistakes are very frequent. You wouldn’t want to make plans or get emotionally attached to the sex of your unborn baby if you used a non-reliable technique to determine if you’re having a boy or girl.

This is one reason why knowing what’s myth and what’s fact is so important.

Sex Prediction Methods

Amniocentesis

Amniocentesis is one of the most accurate methods of determining sex before the birth, with near 100 percent accuracy. However, the test is rarely done for the sole purpose of predicting sex because of the medical risks of the procedure.

During an amniocentesis (amnio for short), a needle is carefully inserted through the abdomen into the uterus and into the amniotic sac. Ultrasound is used to guide the needle, to avoid harming the baby. The needle is then used to draw up amniotic fluid.

This amniotic fluid contains genetic material from the baby. Through chromosomal analysis, certain genetic disease can be detected. It’s also possible to determine the sex of the baby, with XX chromosomes indicating a girl and XY indicating a boy.

(There are some genetic disorders where the sex chromosomes aren’t typical. For example, XXY in Klinefelter syndrome or XO in Turner’s Syndrome. However, these cases are rare.) 

Amniocentesis is usually done when there is a risk or concern for genetic anomalies, like when the mother is age 35 or older, if other testing has indicated a possible risk, or if a hereditary disease is part of the family history.

If you’re already having the testing for those medical reasons, also asking for sex determination may be possible.

Amniocentesis comes with a small risk of infection and risk of miscarriage. Depending on which study is being referenced, the risk of miscarriage may range between 1 in 200 and 1 in 700. The risk is also dependent on the skill of the technician and when the amnio is done. (The earlier in the pregnancy, the more risk of pregnancy loss.) There is also a very small risk the needle will harm the baby.

Chorionic villus sampling (CVS)

Chorionic villus sampling (CVS) is another very reliable method of sex prediction, with near 100 percent accuracy. However, like amniocentesis, because it is invasive and comes with medical risk, it is rarely done solely to determine the sex of the baby. 

CVS involves taking a sample of tissue from the placenta (specifically, taking a sample from the villi, hairy-like projections of placental tissue) and testing that tissue for chromosomal abnormalities. The tissue sample may be also be used to determine if the baby is XX (a girl) or XY (a boy).

As with amniocentesis, there are risks, including a rare possibility of infection and an increased risk of pregnancy loss. CVS is never done solely to determine the sex of the baby, but it is possible to request sex prediction along with the genetic disease screening.

Non-invasive prenatal testing (NIPT)

A relatively new form of prenatal testing, non-invasive prenatal testing (NIPT) is a low risk method of detecting the risk of certain chromosomal abnormalities. The test works by looking for DNA strands that are free floating in the blood stream, also known as cell-free DNA (cfDNA). Everyone has their own cfDNA floating around the bloodstream, but a pregnant woman also has the cfDNA of her unborn child. This fetal cfDNA comes from the placenta, which is almost genetically identical to the fetus. 

NIPT is primarily used to screen for the risk of congenital diseases, and if there does seem to be an increased risk, more invasive testing (like CVS or amniocentesis) may be performed to diagnosis the specific condition.

NIPT can be used to determine the sex of the unborn baby by looking for Y-chromosome cell-free DNA fragments. If present, this indicates the mother is likely pregnant with a boy. If there are no Y-chromosome cfDNA present, then it’s assumed the baby is most likely a girl.

How accurate is NIPT at determining the sex of the baby? It's difficult to say, as the test is so new. Some things that can affect result accuracy include when the test is done (too early in the pregnancy is less accurate), the quality of the blood sample, and detecting possible undiagnosed genetic conditions of the mother.

However, some studies have found that if the NIPT test is completed after 8 weeks gestation, the accuracy is nearly 100 percent for sex determination.

This near 100 percent accurate doesn’t refer to when the test results are determined to be inconclusive. One paper determined that between 10 and 20 percent of NIPT samples come back with “inconclusive” results. In other words, for every 10 women who have the test done, between 1 and 2 of them won’t get any results.  

What if you have twins? NIPT testing can be used to tell you if you’re having only girls or at least one boy. It can’t, however, determine if you’re having one boy or two boys—only that there is at least one boy or doesn’t appear to be any boys.

Traditional Ultrasound

Learning whether you’re having a boy or girl during the second trimester ultrasound is the most popular and well-known method of sex prediction. Typically completed between 18 weeks and 22 weeks of pregnancy, this routine ultrasound is intended as a screening method. It allows the doctor and parent(s) to know everything is hopefully going well with the unborn baby.

During this ultrasound, it’s also possible for the technician to see with near 100 percent accuracy whether you’re having a boy or a girl. They look for either what’s called the “hamburger” sign (for a girl) or, for a boy, the penis may be clearly visible on the ultrasound.

You may ask the technician to tell you during the ultrasound what you’re having. Or, you can ask them to write it down on a piece of paper and place that paper in an envelope. You may request this if both parents are present but only one wants to know the sex of the baby, or if you’re planning a gender reveal party where you want the sex to be a surprise even for you and your partner. For a surprise gender reveal party, you might hand your results to a professional event planner, a friend planning your party, a baker (who is making you a color-revealing gender cake), or a florist (who might pack a box of balloons to open at your party.)

There’s very little risk to the mother and baby with ultrasound. However, ultrasound exposure isn’t completely risk free. Repeated or prolonged exposure may be harmful, and this is especially so in the hands of an unqualified tech.

Fetal Sex Ultrasound Mistakes

Can your ultrasound results be wrong? Yes, it’s possible. Unlikely, but possible.

Ultrasound mistakes are more likely if:

  • Conducted during the first trimester: While it is possible to look for fetal sex signs before 14 weeks gestation, mistakes are more likely. Making decisions or getting emotionally attached to a sex determination completed early in pregnancy is not a good idea.
  • If there are genital anomalies: Congenital anomalies of the reproductive organs can make sex determination tricky or impossible. 
  • It appears to be a girl: Especially early in pregnancy, a “girl” may be a boy whose penis is “hiding” or not clearly visible because of the position of the baby or the mother’s uterus. Ultrasound technology is amazingly accurate and mistakes are unlikely post-18 weeks gestation. That said, in less than 1 percent of cases, it happens.
  • Inexperienced ultrasound tech: The experience and skill of your ultrasound tech can affect the accuracy of sex determination.

How Accurate Are Sex Determinations?

One study that included 640 pregnancies found that:

  • Sex determinations made after 14 weeks were 100 percent accurate.
  • Results were 75 percent accurate when made between 11 and 14 weeks gestation.
  • Results were only 54 percent accurate when made for fetuses younger than 12 weeks.

Ramzi's Ultrasound Method

The Ramzi ultrasound method sounds very scientific but turns out to have very little scientific evidence to back it up. Many sites claiming the method is medically valid attempt to link to the original study. However, the study link is dead, and the original study doesn't seem to be available online.

The Ramzi ultrasound method claims you can determine whether you’re having a boy or girl based on which side the placenta is in the uterus. If it’s on the left, it says you’re having a girl. If it’s on the right, this supposedly means you’re having a boy.

There are no peer-reviewed studies finding this method to be accurate at this time. Also, those who claim the method works argue about how to know if the ultrasound is showing the right right. You could be looking at a mirror image. Or, the picture might be taken from the side, as opposed to from the front of the abdomen. In other words, you can’t know from looking at a printed ultrasound photo which side the placenta is on unless you specifically asked the technician what orientation was used to capture the image. 

There are businesses and websites online that will take your early ultrasound pictures and make a sex determination based on the Ramzi method. This is most likely a waste of money.

It’s better to either wait until a second trimester ultrasound can give you more accurate results, or consider NIPT testing instead (which can give results as early as 9 or 10 weeks gestation.) 

At-Home Tests

Urine Tests

There are a number of at-home urine-based gender “test” kits available for purchase online. None of the urine-based gender tests are scientifically accurate.

In fact, some of these tests straight out say on the box that they are “for entertainment” purposes only. Others, you’ll find the disclaimers only on the paper insert. All these tests warn users not to make any “financial or emotional” decisions based on the results.

Don’t be fooled by the tests that offer “100 percent” satisfaction or a money back guarantee. They are relying on the fact that the majority of people won’t ever ask for their money back, and the fact that the test will predict the gender accurately about half the time from a pure odds perspective.   

Genetic Tests

There are also at-home NIPT genetic tests available. These tests are not urine based, but require a blood sample. Two major brands include SneakPeek Test and Nimble Diagnostics.

Unlike the at-home urine tests, these do have a scientific basis for the results. These tests use non-invasive prenatal testing (NIPT), as described earlier in this article. They are looking for cell-free DNA fragments, which are DNA strands that are free floating in the blood stream. If Y-chromosome cell-free DNA is found, this means the mother is having a boy.

While there is little risk to this test, and the accuracy of the results are around 95 percent if the sample is taken as directed, you’re not guaranteed to receive results. You may get an “inclusive” result, either because the sample was taken too early (you should be at least 9 weeks pregnant) or the blood sample wasn’t high enough quality for other reasons.

It’s unclear how frequently women receive an inconclusive result.  

Also, if you’re not very careful about collecting the sample, you could accidentally get a “male result” from contamination. For example, if your hand has physical contact with a male, the test can pick up his Y-chromosomes cell-free DNA. This is why extremely thorough hand washing is required before taking the sample.

Fact vs. Fiction

Morning Sickness

There’s folk wisdom that says that you’ll have worse morning sickness if you’re having a girl. This is actually partially true.

Research has found that women who develop severe morning sickness—hyperemesis gravidarum—are more likely to be carrying a girl than a boy.

Important to note, however, is that the studies have not found a difference when looking at “regular” morning sickness. This difference in sex ratio appears only in severe morning sickness. 

Also, hyperemesis gravidarum isn’t a certain sign you’re having a girl. You’re just more likely to be carrying a girl. How much more likely?

One study found that women who were hospitalized for hyperemesis gravidarum were 50 percent more likely to be pregnant with a girl. If they were hospitalized for three or more days, the odds jumped to 80 percent more likely.

Mother’s Intuition

Some claim that a woman “can just tell” if she’s having a boy or a girl, not based on any particular symptoms or signs, but relying on a “mother’s intuition.”

A small study found that women with more than 12 years of education could predict the sex of their unborn child with 71 percent accuracy, better than they could just by chance. Less educated women were less successful, guessing the sex correctly only 43 percent of the time. It's unclear how the mother's education level would impact their "intuition" skills.

However, other studies have not found a mother’s intuition to be a reliable sex predictor.

Fetal Heart Tones

Some have claimed that the fetal heart tones for girl babies are faster than they are for boy babies. Studies have found this to be untrue.

There’s no statistically significant difference between the heartbeat of a female fetus and a male fetus. 

Belly Shape and Size

There’s a common folk saying that if a woman “carries” high (with her belly looking more like a basketball under her shirt), then she’s having a boy, and if she carries low, that means she is having a girl.

The truth however is that you can’t determine the sex of the baby based on belly shape. Your belly shape has more to do with your personal genetics, your weight before and during pregnancy, and how many pregnancies you've had.

Drano Test

This sex-prediction myth claims that you can determine whether you’re having a girl or boy by mixing your urine with Drano. Researchers have actually tested the Drano theory out in a lab setting. And, no, it doesn’t work. You can’t predict sex using caustic plumbing chemicals.

The Drano test is not only untrue, but can also be dangerous. Drano fumes can be extremely toxic. You don’t even want to be playing with Drano when you’re not pregnant, and even less so when you’re expecting.   

The web has various “results” listed, with some websites claiming the urine will turn brown or blue for a boy and green for a girl, while other sites claim it’ll turn blue for a girl and green for a boy. There’s no consensus on what colors mean what—partially because it’s not based on fact.

Baking Soda Test

According to the baking soda test, mixing your urine with baking soda can tell you if you’re having a boy or a girl. If the mixture bubbles and fizzles, they say you’re having a boy. If nothing happens, they say you’re having a girl.

The baking soda test does not work—you can’t tell what you’re having based on how acidic your urine is.

The acidity of your urine can be affected by many things, including how hydrated you are, your diet, and your physical activity level. But there’s no evidence that your urine pH changes based on the sex of your unborn baby.

The good news, however, is that this test is harmless. Unlike Drano, baking soda is a safe substance. If you want to mix your urine with baking soda just for fun, you could—but it won't tell you the sex of your baby.

When You Conceived

There’s quite a lot of folklore connecting when you conceived with whether you’ll have a boy or a girl. There are Ancient Chinese Gender charts, which claim that the month you conceived and the mother’s age can tell you whether you’re having a boy or a girl. Then, there are some folk stories that claim conception during an odd month will give you a girl and conception on an even month will give you a boy. There are also theories that the season you conceived can affect whether you have a boy or a girl.

The Ancient Chinese Gender chart is not an accurate predictor of sex. Also, as you likely already guessed, whether you conceived during an odd or even month won’t change the sex of your child.

However, the seasons may play a role in conception and the sex of your child. A study of approximately 14,000 births found that pregnancies conceived in the fall were more likely to be boys, while babies conceived in the spring were more likely to be girls.

Of course, a good amount of boys and girls were conceived in both seasons, and not all pregnancies conceived in the fall are boys.

The “Ring Test”

The “Ring Test” works like this. You take a ring (any ring, but many people use their wedding ring) and hang it on a string. Then, you hold the string—with the ring dangling down from it—over your belly. The ring shouldn’t touch your belly, but hover over it.

If the ring moves in circles, you’re having a boy. If it moves from side to side, you’re having a girl.

While it's fun to try (and totally harmless) the ring test is also a myth—there’s no scientific validity to it.

The Expectant Father’s Weight

Another popular old wives tale goes like this. If the father gains significant weight, then they say the mother is carrying a boy. If he doesn’t gain weight, then the mom is carrying a girl.

There’s no medical evidence that this is true. However, it is true that some men will gain weight and even experience pregnancy symptoms like nausea along with their partners. This is called Couvade syndrome, or sympathetic pregnancy. It’s not connected, though, to the sex of the unborn baby. 

Food Cravings

The folk wisdom says that if you’re craving sweets and all things dairy, you’re going to have a girl. If you’re craving savory, salty, or spicy, you’re going to have a boy.

While there’s no question that some women experience food cravings during pregnancy—one study estimated that between 50 and 90 percent of women craved a specific food at least once when pregnant—there’s no evidence that food cravings are linked to the sex of the fetus.

There is evidence to suggest that women pregnant with boys may eat more calories overall. It's unclear how you could measure this "more than average" consumption of food enough to determine if you're expecting a boy.

Mood Swings

The folk wisdom says that if you have major mood swings, then you’re probably pregnant with a girl, but if you’re having trouble controlling your temper, then you’re having a boy.

The reasoning behind it seems solid enough. Perhaps your estrogen levels are higher with a girl and testosterone levels are higher with a boy? Hormones do impact mood, in both men and women. However, women don’t have higher estrogen when pregnant with girls or higher testosterone when they are pregnant with a boy. (The amniotic fluid may have higher concentrations of particular sex hormones demanding on the sex of the fetus, but this doesn’t impact the mother’s hormone blood levels.)

Mood swings during pregnancy are a real thing. However, there’s no medical evidence that your mood says anything about the sex of the fetus.

Hair, Skin, and Your “Glow”

There are all kinds of myths surrounding your appearance with the sex of your baby. If you’re having a girl, they say you’ll have oily skin and dull hair. Some say you’ll have a “special glow” if you’re carrying a girl. Others say that girls “steal their mother’s beauty” and cause acne.

There’s no evidence any of these things are true. You can have gorgeous pregnancy hair and a radiant “expecting” glow whether you’re expecting a boy or a girl.

A Word From Verywell

More than half of men and women say they want to find out the sex of their baby before the birth. It’s natural to seek easy ways to get the answer, especially methods that might give you answers earlier rather than later.

However, you don’t want to get emotionally attached to a sex prediction that is based on faulty science or is pure myth. The most reliable methods of sex prediction are ultrasound after 14 weeks, genetic tests like those conducted during an amniocentesis or chorionic villus sampling (CVS), or the newer non-invasive prenatal testing (NIPT) blood test.

If you find out that the sex of your baby isn’t what you hoped for, try not to feel guilty for being upset. Gender disappointment is real, common, and nothing to be ashamed of. Talk to someone you trust about how you feel. Be reassured that you will bond and eventually fall in love your baby, regardless of their sex. If you’re really struggling, professional counseling may help.

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