Baby Sex & Heartbeat: Can You Determine Baby’s Sex By Fetal Heart Rate?

Your baby’s heart is extraordinary. It is one of the first sounds from your baby you hear during pregnancy and is vital for delivering oxygen to your baby‘s growing brain and body. The idea that heart rate can predict baby sex, or gender, is an intriguing topic often discussed among expecting parents, despite lacking conclusive evidence. While these discussions are engaging, the scientific validity of using heart rate as a gender predictor is questionable. But is your baby‘s heartbeat an accurate gender or sex prediction method? In short, no, fetal heart rate is not a reliable indicator of male or female sex, nor a definitive gender predictor. However, you can learn a lot by listening to your baby‘s heartbeat; see what’s below to explore prediction methods for sex ranging from traditional old wives’ tales to modern scientific approaches, each with varying accuracy in predicting the sex of your baby.

The wives’ tale explained

Old wives’ tales are stories, myths, or superstitions centered on women’s health, traditionally passed down from “wives”, or older generations of women, to younger women as a way to guide them in navigating pregnancy or puberty before modern research and studies provided us with scientific alternatives.¹

Myth: If your child’s fetal heart rate is below 140 bpm (beats per minute) it’s a baby boy, and if it is above 140 bpm, it is one of the signs of a baby girl.

While a fun idea, this heart rate gender prediction method is just an outdated old wives’ tale.

Why might some expecting parents believe in this method?

First-time parents might be susceptible to gender prediction methods due to pregnancy inexperience, excitement, and external pressure to know their baby’s sex early. Additionally, anecdotal evidence from social media, within social circles, or from close family members may also serve to further reinforce this myth’s influence.²

This prediction method is rooted in tradition, often providing comfort to expecting parents. While there are anecdotal tales from parents both for and against this method, the science behind it doesn’t hold up.²

While there are methods like the sneak peek test that determine your baby‘s sex early, unfortunately, whether the fetal heartbeat is 110, 150, or 170 beats per minute, listening to your baby‘s heart rate is not a reliable way for predicting a baby‘s natal sex.

What is fetal heart rate, and how can we know a fetus’s cardiac activity?

When we say fetal heart rate, or FHR, we are referring to a fetus’s bpm while in utero. Fetuses’ heartbeats can be measured by a certified medical professional with an ultrasound or at home with a Doppler device.³

A fetus’s cardiac activity varies with age in pregnancy, with a range from 90 to 170 bpm..

• Early pregnancy (5 to 7 weeks): A healthy FHR can range from 90 to 110
• 8 to 12 weeks: Can rise up to 170 bpm, with a normal range being between 120-160 bpm
• 12 weeks to birth: FHR will usually drop down to 110-130 bpm

In addition to your baby’s age and your pregnancy stage, BPM can also vary according to activity level. Such variations make gender or sex prediction through heart rate unreliable.^2,4

Baby heartbeat & sex – research busts the myth

Two significant studies have scrutinized this heart rate to gender prediction method. One study was published in 2006 and the other in 2015; both sought to address the question “Is there a significant difference between a baby boy‘s heartbeat and a baby girl ‘s?”

D.S. McKenna, G. Ventolini, R. Neiger, and C. Downing examined resting fetal heart rates in 477 pregnant women that were less than 14 weeks into pregnancy . As published in their paper “ Gender -Related Differences in Fetal Heart Rate (FHR) During First Trimester”, 244 women had girls (51%) and 233 (49%) had boys with corresponding male and female fetal heart rates of 154.9 ± 22.8 and 151.7 ± 22.7 bpm respectively. While an average heart rate difference of ~3bpm was identified, this falls well within the margin of error therefore there is no statistical significance between male and female heart rate of fetuses during the first trimester of pregnancy and heartbeat is not a reliable method to determine newborn natal sex.

In “First trimester fetal heart rate as a predictor of newborn sex” published by L.A. Bracero, D.J. Seybold, S. Witsberger, L. Rincon, A. Modak, and L.V. Baxi, the authors studied medical files and ultrasounds of 655 women 8-13 weeks pregnant to compare first-trimester fetal heart rates with newborn sex at delivery. Findings show the average for girls was 167.0 ± 9.1 bpm, and for males, 167.3 ± 10.1 bpm. While the error margin in this study was smaller, they too found no significant difference in FHR between males and females, despite the common myth that a faster FHR indicates a female fetus.

What does your baby’s growing heart tell you?

Sex or gender prediction based on heart rate may not work, but your baby’s heartbeat can provide great insight into the state of his or her heart health.

• A baby’s heartbeat begins to grow immediately after conception and only takes 8 weeks to form completely.
• Does your baby’s heartbeat seem a bit fast? That’s because an adult human’s heart rate ranges from 60-100 beats per minute, while a baby’s heart rate may be 110-160 beats per minute in the womb. Understanding how gestational age affects heart rate can further enhance your knowledge of fetal health during pregnancy.
• A mother’s heart rate is likely to change during pregnancy; a woman will typically see an increase of approximately 7 beats per minute when pregnant, reflecting both hormonal influence and the body‘s adaptation to a growing fetus.
• Healthy fetal heart rate, measured using a baby heartbeat monitor, is commonly in the range of 110-160, and may vary up or down by up to 25 bpm throughout the day⁵ due to physical activity or eating, as well as throughout the different stages of pregnancy.

• Fetal heart rate may increase from 110 beats per minute at week 5 to 170 at around 10 weeks and then drop to approximately 130 near the time of delivery.

You can even do fetal heart rate monitoring from the comfort of your home with your own fetal doppler! This is a great way to bond with your little one before they arrive.

When sex is determined – sex vs gender

Your baby’s sex is founded on biological and physiological characteristics and is set once the sperm meets the egg. Sex is determined at conception, before your baby has a heartbeat, and even before you know you’re pregnant. Your little one inherits either an X or Y chromosome from the sperm and an X chromosome from the egg. Accordingly, “natal sex” is set such that females carry an XX chromosomal pattern, while males carry an XY chromosome composition.

Gender on the other hand is recognized by the World Health Organization as a social construct that refers to a set of characteristics, norms, and behaviors that are unique to males and females. A baby’s gender is not always set at birth, may differ from the person’s designated sex, and can vary from one society to another. In the U.S. gender is historically thought to be binary however gender roles and gender behaviors are ever-evolving.

Reliable tests to reveal your baby’s sex

Now that you know that using a baby heart rate gender prediction is an old wives’ tale, here are some non-invasive tests that you can take to reveal the fetal sex:

Ultrasound scan

This is the most common form of fetal sex testing that is usually performed in the second trimester of pregnancy, typically during the 18th to 20th week of pregnancy. The ultrasound imaging procedure can identify the genitalia of the fetus by examining its measurements and can also scan for physical abnormalities.

Gender blood test

This testing requires a blood draw and can be performed during early pregnancy, allowing you to learn your baby’s sex earlier than ever before! There are also blood tests further into pregnancy that check for possible genetic abnormalities.

Genetic testing

Also known as a prenatal diagnostic test, genetic testing looks for genetic abnormalities by examining cells and amniotic fluid. While this method can reliably determine fetal sex, it helps confirm if a fetal disorder is present and comes with greater risk to the unborn baby and mother. In Amniocentesis, a needle is used to withdraw amniotic fluid and in Chronic Villis Sampling (CVS), a tissue sample from the placenta is taken and used for testing. Genetic testing is not commonly recommended by your doctor unless a blood test suggests likelihood for a chromosomal condition.

Noninvasive prenatal testing (NIPT)

This non-invasive form of blood testing is primarily designed to screen for risk of genetic disorders, but can determine a baby’s sex as early as 9 weeks.³

Additional baby gender reveal myths

It is only natural that there have been countless other methods used throughout history to predict a baby’s sex. Like our earlier pregnancy myth, these wives’ tales aren’t reliable gender tests but can still be fun for you and your family!

• Ring Test – A popular wives ’ tale involves a ring, usually the wedding ring. By dangling the ring on a string over the pregnant woman’s belly, one can determine the sex based on the movement. If the ring swings back and forth, it is a boy, while if it swings in a circular motion, then it is a girl.
• Linea Nigra – Others believe that the “linea nigra” holds the key. Commonly referred to as “the pregnancy line”, this is a dark vertical line that runs down the middle of the abdomen. How long the line is can supposedly tell you the sex. If the linea nigra stops at the belly button, then it is a girl. However, if the line continues to the xiphoid, which is the tip of the sternum, then it is a boy.
• Mirror Test – Then there is the classic: if you look better than ever, then it must be a boy. Meanwhile, if you are looking worse than usual, then it is a girl, because she is stealing your looks! You can read more signs you’re having a boy or signs you’re having a girl right here with SneakPeek.
• Chinese gender prediction – This is a traditional method that was used to determine sex based on conception date and the mother’s date of birth. Unfortunately this is not a reliable method, and still has a 50-50 chance of predicting your baby’s sex. Try it out and see if it ends up being accurate!
• Carrying high or low – This tale theorizes that a high baby bump means you are carrying a girl, while a low bump means you are carrying a boy.

Of course, none of these old wives’ tale pregnancy myths are backed by scientific evidence or research. Nonetheless, they are simple and fun tests to do on your own.

Get to the heart of the gender question with SneakPeek

You shouldn’t have to wait too long to get to know if your baby’s extraordinary heart belongs to a beautiful baby boy or a gorgeous little girl. Discover your baby’s sex with the SneakPeek Gender Prediction Test.

The Early Gender Prediction Test is the only one that can determine a baby’s sex as early as 6 weeks into pregnancy and has proven to be over 99% accurate in laboratory studies. Even better? You can take the gender blood test in the comfort of your home.

Get to the heart of your gender questions with the SneakPeek test.

Skip the wait for shipping and pick up SneakPeek Snap at select Walmart, CVS, and Walgreens stores. Just look for the kit in the pregnancy aisle, and take your test today!

Editorial Policy

At SneakPeek, our commitment is to provide accurate, up-to-date, and reliable information to empower our readers. Our content is thoroughly researched, reviewed by medical experts, and fact-checked to ensure its credibility. We prioritize the well-being and education of our readers, and our editorial policy adheres to the highest standards of integrity and accuracy in all our articles.

This post has been reviewed for accuracy by the following medical professional:

Katie Smith, MSN, APRN, CNM

Katie Smith is a seasoned Certified Nurse Midwife and a nurturing mother to six children, offering a unique blend of professional expertise and personal experience. She is the founder of Birth Your Way Midwifery and Women’s Wellness Center in Bay County, Florida. Katie's comprehensive approach to care is informed by her hands-on experience in motherhood and her passion for empowering women through their birthing journey. Her dedication extends beyond her center as she actively engages in community wellness and family health education.

Sources:

1. Pampers. Boy or Girl? 34 Old Wives’ Tales for Predicting a Baby’s Gender. https://www.pampers.com/en-us/pregnancy/pregnancy-announcement/article/old-wives-tales-gender-prediction
2. Raleigh OB/Gyn. Can Fetal Heart Rate Reveal Your Baby’s Gender? Separating Fact from Fiction.  https://www.raleighob.com/can-fetal-heart-rate-reveal-your-babys-gender/
3. What To Expect. Does the Heartbeat Gender Prediction Method Work? https://www.whattoexpect.com/pregnancy/screenings-and-tests/fetal-heart-rate-gender
4. Healthline. Can a Baby’s Heart Rate Predict Its Sex? https://www.healthline.com/health/pregnancy/baby-heart-rate-predicting-gender
5. Johns Hopkins Medicine. Fetal Heart Monitoring. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/fetal-heart-monitoring