Pregnant couples have always wondered about finding out the sex of their unborn child. One of the most common and oldest myths is that the baby’s heart rate will tell you if you are having a boy or girl. The legend predicts that an over 140 beats per minute heartbeat is a girl and under that is a boy. Now that early pregnancy testing and Doppler technology have been invented, anxiously awaiting parents wonder if the legend holds a grain of truth. Although it’s hard not to guess for hints using an ultrasound, physicians urge restraint in using fetal heart rate as a tool in gender identification. Here we will discuss what is fetal heart rate, what influences it, and scientifically if there is any relation between heartbeat and sex. We will also briefly discuss how and when the sex is actually determined, and when you can know the sex of your baby for certain. We will separate facts and myths regarding baby heart rates.
What Is Fetal Heart Rate?
Fetal heart rate (FHR) is the number of your baby’s heartbeats per minute (bpm) during pregnancy. One of the key signs health care professionals rely on to assess your baby’s well-being and health, it’s a sign of normalcy.
- Normal Fetal Heart Rate Range: Normal fetal heart rate is typically 110 to 160 bpm.
- Early Pregnancy Heart Rate: It may start as early as 90 bpm in the first trimester and may increase very rapidly.
- Peaks Around Week 9-10: A maximum of 170 bpm is achieved here before it decreases slowly to normal again.
Fetal heart rate is monitored with Doppler ultrasound, fetal monitors, or with a hand-help device during a prenatal examination. Abnormality from this can result in additional medical tests.
The Heart Rate Gender Prediction Theory
This fetal heart rate theory that predicts the gender of a baby is folklore. General theory is:
- Above 140 bpm = Girl
- Below 140 bpm = Boy
Supporters of the theory describe how girls’ heartbeats are quicker, but boys will have slower, more consistent beats. The theory has been around for decades and crops up periodically in books about pregnancy, parent websites, and even baby showers. How accurate is it then?
What Does Science Say?
Medical research has contradicted the myth that fetal heart rate was something which could be used to determine gender. Several peer-reviewed articles have tested this presumption:
- In 2006, a paper in “Fetal Diagnosis and Therapy” measured first-trimester fetal heart rate and concluded that male and female fetuses are just as different.
- A 2018 journal article in “Ultrasound in Obstetrics & Gynecology” made sure that fetal movement and gestational age have more to do with heart rate variability than gender.
- A 2021 clinical observation also reached the same conclusion that even if heart rate does change, it is not a gender decision-making factor.
In short, fetal heart rate is a good health indicator but not a gender one.
What Impacts Fetal Heart Rate?
Fetal heart rate may be altered by an infinite number of things and none of them are related to the sex of the baby. They are:
- Gestational Age: Throughout pregnancy, there is an increase in heart rate early in pregnancy and then it stabilizes thereafter.
- Fetal Activity: As with adults, when the fetus moves more rapidly, the heart rate will accelerate for a short while.
- Maternal Health: Fever, stress, or some medication will disrupt fetal heart rate.
- Time of Day: Circadian rhythms could be the cause of normal variation.
As there are numerous factors influencing fetal heart rate, it is scientific but not trustworthy to depend on it for gender identification.
When Is Baby’s Gender Determined?
Sex is determined at conception, depending on whether the sperm contributes an X or a Y chromosome:
- XX = Female
- XY = Male
Even though sex is determined early, it will not be evident on imaging at first. This is when you actually can:
- Ultrasound (18–22 weeks): Most common test used to take a peek at the baby’s gender.
- Non-Invasive Prenatal Testing (NIPT): Blood tests done early 9–10 weeks may evaluate fetal DNA.
- Chorionic Villus Sampling (CVS) or Amniocentesis: Tests that also show gender, typically performed as part of genetic disease screening.
The above tests are the only medically correct methods of determining a baby’s gender early.
Medical Tests That Correctly Disclose Baby’s Gender
Because there are so many myths about fetal heart rate, there are quite a few clinically verified methods of determining your baby’s gender during pregnancy. They are science-based and range in accuracy, time, and risk.
- Cell-free DNA screening (Panorama, Harmony, and Maternit21) is done as early as week 9. It is an office blood test that analyzes fetal DNA fragments in the mother’s blood. While most universally applied in the screening for genetic disorder, it also determines the sex chromosomes. Providers report getting as close as 100% accurate in the detection of fetal sex. The test is not routinely warranted in women with multiple gestations, or donor egg, or history of bone marrow transplant.
- Amniocentesis and Chorionic Villus Sampling (CVS) are both diagnostic tests which detect chromosomal disorders—and even reveal the sex of the infant. CVS is performed 10–13 weeks pregnant, and amniocentesis 14–20 weeks. Both pose a minimal risk of miscarriage and are usually reserved for women with high-risk pregnancies.
- Finally, the routine anatomy ultrasound weeks 18–20 should then be able to reveal gender visibly. While non-invasive, it is subject to fetal position and the skill of the tech.
These choices are far superior to heart rate guessing for safe and accurate disclosure of your baby’s gender.
Why Getting It Right Is Important
For some couples, having the baby’s gender revealed ahead of time is a personal choice. For others, it may assist:
- Preparing emotionally and practically.
- Arrange for nursery color or baby names.
- Get educated on the potential genetic or sex-linked diseases.
Earliest gender identification might be necessary in atypical medical conditions to rule out or include inherited disease like hemophilia or Duchenne muscular dystrophy.
FAQs
Q1: Can a fetal heart rate of 150 bpm mean I’m having a girl?
Not necessarily. A fetal heart rate of 150 bpm falls within the normal range and does not predict gender. Both boys and girls can have heart rates in this range.
Q2: When is fetal heart rate first detected?
Typically, a baby’s heartbeat can be detected via vaginal ultrasound around 5.5 to 6 weeks of pregnancy.
Q3: Is too rapid a heart rate dangerous to my baby?
Not necessarily. Tachycardia is normal. Recurring rates over 160 bpm or below 110 bpm should be followed up by a health care professional.
Q4: Will stress influence the heart rate of my baby?
Yes. Stress, infection, or maternal medication may influence acute fetal heart rate variability.
Q5: How is it best to know gender before birth?
The most effective and most common ones are second-trimester ultrasound and NIPT.
Conclusion
In spite of the myth that fetal heart rate would tell your baby’s gender, pregnancy folklore, science tells a different tale. Time and again, research proves that there is no logical connection between a baby’s heart rate and sex. Instead, fetal heart rate is a significant indicator of your baby’s health—not gender. There are accurate, safe, and non-invasive methods of gender revelation with today’s medicine with pregnancy blood work and ultrasound. If you’re curious about your baby’s gender, speak with your healthcare provider about the best timing and methods for accurate results. Most importantly, remember that the health and well-being of your baby are what matter most—regardless of whether you’re expecting a boy or a girl.
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