Can belly shape predict sex?

The idea that a baby bump’s shape or position reveals sex is one of the oldest pregnancy superstitions around. Here’s the most common version of the lore:

• Carrying high? You’re having a girl.
• Carrying low? You’re having a boy.

Beliefs like these likely developed over centuries of folk wisdom. While they’re entertaining to consider, it’s important to take these speculations with a grain of salt. Today, science has confirmed that your baby’s sex does not impact how your belly looks.

Instead, baby bumps are shaped by factors like maternal anatomy, how many little ones you’re carrying, and a baby’s own size and position.

Reliable Methods for Predicting Sex

If you truly want to know your baby’s sex, these are the most clinically reliable methods for doing so:

• At-home gender DNA tests – Home testing options, like the SneakPeek Early Gender Test®, can quickly, safely, and conveniently let you know if you’re expecting a boy or girl as soon as 6 weeks into pregnancy. These tests use a small sample of maternal blood to screen for fetal DNA, which can reveal your baby’s predicted sex.
• Non-invasive prenatal testing (NIPT) – What is an NIPT test? NIPTs are a type of blood test that analyzes fragments of fetal DNA in the maternal bloodstream to identify the baby’s risk of certain medical conditions. However, fetal DNA can also reveal sex, meaning a secondary function of NIPTs is understanding your baby’s sex as early as 8 weeks into pregnancy.
• Chorionic villus sampling (CVS) – CVS may be performed at 10 to 13 weeks, but it’s usually only used if your baby is at risk of a chromosomal disorder. Like NIPTs, the main purpose of CVS is not to determine sex, especially given the invasive nature. The process must be administered by a healthcare provider as it involves retrieving a sample of placental tissue.
• Amniocentesis – Amniocentesis is usually performed between 15 and 20 weeks of pregnancy. Like CVS and NIPTs, its ability to predict sex is a secondary function. The main purpose of amniocentesis is screening for genetic conditions. The procedure involves having a sample of amniotic fluid taken from your amniotic sac.
• Ultrasounds (anatomy scans) – Anatomy scans are typically offered in your second trimester, around 18-20 weeks of pregnancy. There are different types of ultrasounds for pregnancy, but at this stage, ultrasounds are usually able to pinpoint a baby’s sex if their reproductive organs are visible.

4 Baby Bump Traits and What They Indicate

While there’s no difference in a pregnant belly between a boy or girl, the shape of your baby bump isn’t necessarily meaningless. Rather, your baby bump shows how your body has adapted to pregnancy.

Traits like shape, width, and height can actually offer clues about factors like:

• Muscle tone
• Your baby’s position in utero
• How many babies you’re having
• Your own body type

Put differently, your pregnant belly is the “lump sum” of your and your developing baby’s characteristics. Let’s dive into four of the most noticeable ones.

Width

Some people describe baby bumps as looking either “wide,” spreading out horizontally, or “narrow,” projecting outwards. Often, how your belly “spreads” has to do with your own body type.

Shorter women, or those with short torsos, may appear wider, simply because their uterus has more room to expand laterally. Those with longer torsos may seem to carry more compactly or have “taller” bumps due to more vertical space.

On the other hand, a “wider” looking bump could also indicate a baby’s position in utero. When a baby is lying transverse (horizontally), it may appear that your bump is wider.

Shape

The shape of your bump—round, “pointy,” neat, or spread—is usually influenced by two factors:

• Your abdominal muscle tone
• Your baby’s position

Diastasis recti (“diastasis”) is a common third-trimester symptom that occurs when the abdominal muscles separate along the midline of the body, allowing the uterus to expand. If this happens to you, it can impact your bump’s shape. You might notice:

• A more pronounced bump, especially in the earlier stages of pregnancy
• A lower carriage
• A “doming” effect when you engage your abdominal muscles

Diastasis is more likely among women who are petite, older than 35, having twins, or have an especially large baby. While it isn’t painful, it can impact how your belly looks before and after pregnancy.

Size

Bump sizes vary widely and can hinge on a range of factors, including:

• How many babies you’re having – More than one, and your bump will be bigger.
• Your own height and body shape – Taller women tend to carry small, while shorter women may appear to carry big. That said, this can often be the result of an optical illusion: If you and your friend are at the same point in pregnancy but stand at different heights, it may appear your bumps are different sizes.
• Your baby’s rate of growth – Healthcare providers use the size of a baby bump to gauge a baby’s growth, measuring fundal height (the length from the top of the uterus to the pubic bone). The further along into your pregnancy, the larger this metric will be.
• Your amniotic fluid levels – Having low amniotic fluid levels, as in the case of oligohydramnios, could make your bump look smaller.

Weight Distribution or Height

Carrying high is a common trait of first pregnancies, when your abdominal muscles tend to be stronger. It’s also natural for your bump to sit higher in the first trimester, when your baby tends to sit higher in your uterus.

Carrying low is more common in later pregnancy, after your ligaments have relaxed and your baby descends into the pelvis, getting ready for birth.

Other Wives’ Tales for Predicting Sex

Belly shape certainly isn’t the only myth people have leaned on for predicting the sex of their babies. Here are a few other classic tales and the science (or lack thereof) behind them.

Glow vs. Acne

According to the old wives ‘ tales, that “pregnancy glow” isn’t universal. If you’re lucky enough to have glossy hair and luminous skin, legend has it that you’re having a boy. If you’re suddenly dealing with acne and seem to lack luster, you can blame your future baby girl.

Is there truth to this myth? No. Any shifts you notice in your hair, skin, and complexion are simply attributable to the hormonal changes you’re experiencing, which can impact every expecting parent differently.

Salty vs. Sweet Cravings

If your pregnancy cravings have taken the form of sugar, spice, everything nice, legend has it you’re having a girl. Devouring salty foods, on the other hand, points to a boy.

In reality, experts suspect the types of cravings you have are influenced by the heightening of smell and taste that occurs during pregnancy. Some think cravings could also be related to any nutritional deficiencies you may have, helping you fulfil your needs while you’re expecting.

Morning Sickness Severity

Experiencing more severe morning nausea and vomiting during pregnancy (NVP), often called “morning sickness,” is said to point to a girl. But here’s the remarkable part—some studies indicate there’s truth to the myth.

In a retrospective report of over 4,300 expecting mothers, those carrying a female fetus reported more NVP than their male-carrying counterparts. That said, other factors can also contribute to NVP, such as:

• Your genetics
• Your diet
• Your body weight
• Your age
• Having a history of motion sickness or migraines

Linea Nigra

The linea nigra is a dark vertical line that often appears on a pregnant belly, stretching from the pubic bone up the abdomen. What is connection between linea nigra and sex? According to a common old wives’ tale, the length of this line can predict the baby’s sex. The legend states that if the linea nigra starts below the belly button and stops there, the mother is carrying a girl.

However, if the line extends past the navel and continues upward toward the ribcage, it is said to signify a boy. While this myth is a fun and visual way for expectant parents to guess their baby’s sex, the line’s appearance is actually caused by pregnancy hormones stimulating melanin production, and its length has no scientific link to the sex of the baby.

Mood Swings

So say the old wives, a moodier expecting parent points to a little girl, while feeling more even-keeled indicates a little boy.

Once again, hormones are the main contributors to your emotional range during pregnancy, and every expecting parent responds to changes in hormones differently. Mood shifts may also be exaggerated by lack of sleep, anxiety, or the stressors it’s normal to feel during a time of major change.

Fetal Heart Rate

The Fetal Heart Rate (FHR) old wives’ tale is one of the most popular sex prediction based on heart rate! This simple folklore says that if your little one’s heart rate is fast, clocking in at 140 beats per minute (bpm) or higher, you’re expecting a girl. But if the FHR is slower, staying under that 140 bpm mark, get ready for a boy!

While it’s certainly a fun piece of pregnancy lore to share with friends, multiple scientific studies have looked at FHR during the first trimester, and the findings are consistent: there is no factual, reliable connection between a baby’s heart rate and their sex. FHR naturally fluctuates based on gestational age and activity—so you can enjoy the guesswork, but don’t count on this tale for definitive answers!

See Who’s Beneath the Bump with the SneakPeek® Test

There are benefits of learning your baby’s sex early like essential planning and peace of mind, there are more reliable ways to know who’s waiting for you at the end of your pregnancy journey!

Expectant parents can learn their baby’s predicted sex as early as 6 weeks into pregnancy with the SneakPeek Early Gender Test®. With over 99% clinically proven accuracy, the SneakPeek Test® remains the highest recommended at-home early sex prediction test by America’s OBGYNs.* Order yours today.

*SneakPeek recommended six to one among 100 OBGYNs surveyed