Before giving birth to a baby, you would hear a lot of rumors and stories surrounding pregnancy. And predicting the gender of your kid in the early stage based on heart rate is one of them. If this number is below 140 beats per minute, you would have a boy. If it is above 140 beats per minute, you would have a girl. In fact, you could not predict the gender of your kid based on the heart rate.


The truth is that the heart of your baby would possibly begin to beat at 6th week of the pregnancy. You could even notice and assess the light flicker on the ultrasound. The range of beat per minute would be from 90 to 110 bpm and then increase each day. This number continue to increase till the peak at 9th week, which is from 140 to 170 bpm and similar in both girl and boy.

What is the scientific relation between gender and heart rate in a baby?

In some recent study, researchers have examined the sonograms from nearly 1000 moms, most of them are not over 14 weeks of pregnancy. This process is repeated again in the next trimester from 18 to 24 weeks, when the gender of baby could also be measured by ultrasound.

To this stage, just 480 people still met the requirements of the study. Amongst the pregnant women, 235 are going to deliver boy babies, while 245 are going to deliver girl babies.

Do heart rates really help to predict the sex? In fact, the average beat of heart for boy babies in the first stage is about 155 bpm (more or less 23 bpm) and about 152 bpm for girl babies (more or less 23 bpm).

In other words, it is impossible to guess the gender of your kid by heart rate as there is not a big difference between this number in boy and girl babies during early stage of pregnancy.

When is gender of your kid determined?

In general, the sex of your kid is determined as soon as the sperm combines with the egg. In other words, gender is set even before you notice of being pregnant. The outer sexual organs will not develop for a short time, but your kid inherits both the X and Y chromosome.

In most situations, a boy baby would carry the XY pattern (genetic information) and a girl one would carry the XX pattern.

You would also surprise to know that the genital of your kid does not immediately develop. In fact, a boy and girl will look quite the same in 4 to 6 weeks after pregnancy. The difference starts to develop after 10 to 20 weeks.

Test that would know the gender

Though the measurement of heart rate, you might not know exactly if your kid is a boy or girl. However, there are a lot of methods that could tell you the gender of your kid before giving birth.

Blood test

Blood test has just been available over the past few years. You could take this at abound 9th week of the pregnancy. In fact, the main purpose of this test is not to measure the gender of your kid, but look for any possible abnormalities in gene. And the sex chromosomes of your kid are amongst them.

It is essential to notice that this type of test is not suggested for people who are using donor egg or carrying multiple or those who have just gotten a transplant of bone marrow.

Any possible results that you get must be verified again with other tests.

Genetic test

In the later stage of the pregnancy, you might be suggested by the doctor to take a CVS or amniocentesis test. Similar to a blood test, this would help you to find out any possible abnormalities in gene. As a result, it could tell you the gender of your kid.

These types of test are more precise than a blood test, but carry several risks of miscarrying and also more invasive.

  • In general, you could take a CVS test after 10 to 13 weeks of pregnancy.
  • The amniocentesis test is often taken later, from 14 to 20 weeks.

However, before deciding to know the gender of you kid by this method, remember to take a careful consideration. Those types of test would have potential risks for your kid, so you are often not suggested to take them unless:

  • You have gotten positive result from a blood test before
  • You used to have a chromosomal abnormality in previous pregnancy
  • You are over the age of 35
  • You have a family with history of several genetic disorders


From 18 to 20 weeks of pregnancy is probably the most suitable time when you would want to know the gender of your baby. A lot of doctors often take anatomy scans at this stage to examine the inner working from toe to head and the features of your kid.

During this process, the doctor would apply gel on the tummy and then take the probe to get pictures of your kid. There will be a wide range of measurements to make sure that your kid are developing well. The doctor would also pay attention to the placenta, levels of fluid surrounding the kid and the body’s system.

The doctor could also see the genitals of your kid obviously on the display and make a quite educational and solid prediction. In general, it is quite difficult to know the gender exactly due to the position of the baby.


It is scientifically proved that you could not predict the gender of your kid in the early stage of pregnancy with just heart rate. In general, the difference in the heart rate between boy and girl baby would be really small. However, this is not a problem since you would be able to know exactly the sex of your kid at later stage by ultrasound test.

Nancy D. Richardson

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