Gender Prediction Theories and Methods – Overview, Accuracy, and More

Baby gender prediction tests have come a long way in recent years, with many options available for expecting parents. These tests use various methods to determine the sex of a baby, including analyzing the mother’s blood, urine, or saliva and even using ultrasound technology. In this article, we will discuss the accuracy of baby gender prediction in all of its available forms.

safe infant sleep in a basket

The Allure of Early Gender Prediction

Throughout history, the mystique surrounding a baby’s gender has stirred curiosity among expectant parents.

From old wives’ tales to cutting-edge medical technology, various methods and theories have emerged to satiate this curiosity.

In this exploration, we will offer details on three popular theories—Ramzi Theory, Nub Theory, and Skull Theory—that have caught the fancy of many looking to have fun with these methods a little sooner.

1. Ramzi Theory

Placental Positioning and Prediction

Overview: The Ramzi Theory purports that the location of the placenta as seen in an early ultrasound can predict the baby’s gender. A placenta on the right side of the uterus is said to indicate a boy, while one on the left suggests a girl.

Origins: This theory stemmed from Dr. Saad Ramzi’s observations. Although it has gained some popularity among eager parents, it’s essential to note that the link provided for further reading does not lead to a direct source, hinting at a lack of substantial scientific backing. Even without that backing, this method seems to produce very accurate results to those who can apply it properly.

Application: During an early ultrasound (around 6-10 weeks gestation), the position of the placenta is observed to deduce the baby’s gender as per this theory. However, it’s crucial to acknowledge that most medical professionals recommend gender prediction ultrasounds to be done after 18 weeks for accurate results.

Accuracy and Reception: The medical community largely regards the Ramzi Theory with skepticism due to a lack of empirical evidence supporting its claims. Even though the accuracy of this method has been questioned, the amount of expectant mothers who have had positive experiences has ended up making it a very popular choice for gender prediction.

2. Nub Theory

The Telltale Nub

Overview: Nub Theory centers around the genital tubercle or ‘nub,’ which is an early form of genitalia present in fetuses irrespective of gender. As per this theory, the angle at which the nub protrudes can hint at the baby’s gender.

Origins: This theory has its roots in medical observations, with some practitioners claiming a fair degree of accuracy when the nub is analyzed during a specific gestational window. However, the provided link does not lead to a direct source on the origins, reflecting a need for more concrete information.

Application: Between 11 to 14 weeks of gestation, an ultrasound can capture the angle of the nub. A higher angle (greater than 30 degrees relative to the spine) suggests a boy, while a lower angle is indicative of a girl.

Accuracy and Reception: The accuracy of this method is contingent on the clarity of the ultrasound image and the skill of the technician interpreting it, but because it is the most scientifically backed method, it has also become the more reliable of the gender prediction theories.

3. Skull Theory

Skeletal Clues

Overview: Skull Theory suggests that the shape and characteristics of a baby’s skull in ultrasound images can indicate gender. Proponents believe that male skulls are more blocky with a prominent brow ridge, while female skulls are rounder with a more subtle brow ridge.

Origins: This theory isn’t grounded in medical science but rather observations by individuals over time, interpreting 2D ultrasound images. The lack of scientific backing makes it more of a fun guess rather than a reliable method.

Application: An ultrasound technician or a keen observer may attempt to deduce gender based on skull shape starting at 11+ weeks

Accuracy and Reception: The medical community does not endorse the Skull Theory due to its speculative nature and lack of scientific evidence supporting its claims. It’s considered more of a fun speculation rather than a reliable gender prediction method.

4. Chinese Gender Calendar

Ancient Astrology Meets Modern Curiosity

Overview: The Chinese Gender Calendar, also known as the Chinese Gender Chart, is an ancient method believed to predict a baby’s gender based on the mother’s age at conception and the lunar month of conception.

Origins: This chart dates back to the Chinese Qing Dynasty and is said to have been found in a royal tomb over 700 years ago. Its traditional roots offer a glimpse into historical gender prediction methods.

Application: By cross-referencing the mother’s age at conception with the year of conception on the chart, a prediction of the baby’s gender is made. However, this method is rooted in superstition rather than science.

Accuracy and Reception: As a method based on astrology and tradition rather than scientific evidence, the Chinese Gender Calendar is not recognized as a reliable method by the medical community. It’s often viewed as a fun and cultural practice rather than a serious gender prediction tool.

5. Mayan Gender Prediction

A Cultural and Historical Approach to Gender Prediction

Overview: Mayan Gender Prediction is a traditional method used by the ancient Maya civilization to predict a baby’s gender based on the mother’s age at conception and the lunar month of conception. It reflects the Mayan culture’s beliefs and practices related to childbirth and astrology.

Origins: This method finds its roots in the ancient Mayan civilization, which thrived in Mesoamerica over a thousand years ago. It was a significant part of Mayan culture, reflecting their close connection to celestial events and their spiritual beliefs.

Application: To predict the baby’s gender using the Mayan method, one must know the mother’s age at conception and the month when conception occurred. These two factors are then used to consult traditional Mayan charts and calculations to make a gender prediction. However, it’s essential to note that this method is steeped in cultural and historical significance rather than scientific accuracy.

Accuracy and Reception: Similar to the Chinese Gender Calendar, Mayan Gender Prediction is not regarded as a scientifically reliable method by the medical community. It is considered a cultural practice and is often used for entertainment or as a way to honor and connect with Mayan traditions. While it may offer insight into the historical customs of the Mayan civilization, it should not be relied upon as a serious gender prediction tool in a medical context.

6. Heart Rate Method

Listening to the Beat

Overview: This method posits that a faster fetal heart rate indicates a girl, while a slower rate suggests a boy. Commonly, a heart rate above 140 beats per minute is said to indicate a female, and below 140 beats per minute, a male.

Origins: The origins of this method are unclear but it seems to be a long-standing belief passed down through generations.

Application: During prenatal visits, the heart rate of the fetus is monitored. Some individuals may use this information to speculate on gender.

Accuracy and Reception: Medical professionals debunk this method, stating that fetal heart rates vary throughout gestation for numerous reasons unrelated to gender. It’s a common misconception rather than a scientifically supported method.

7. Old Wives’ Tales

A Blend of Folklore and Fancy

Overview: Old Wives’ Tales encompass a variety of beliefs and methods purported to predict gender, ranging from the shape of the mother’s belly to her food cravings.

Origins: These tales have been passed down through generations, often reflecting cultural beliefs and observations.

Application: These methods are often shared among friends and family, and applied in a lighthearted manner.

Accuracy and Reception: There is no scientific evidence supporting Old Wives’ Tales for gender prediction. They are often seen as fun, traditional, and cultural practices rather than reliable methods for determining a baby’s gender.

Here’s a brief list and summary of some common Old Wives’ Tales related to gender prediction:

Shape of the Belly

It’s often believed that carrying high indicates a girl, while carrying low indicates a boy. The shape of the belly, whether round or oval, is also sometimes thought to indicate gender.


Some tales suggest that craving sweet foods indicates a girl, while craving salty or sour foods indicates a boy.

Ring Test

A ring, typically the mother’s wedding ring, is attached to a string and held over the belly. If it swings in a circular motion, it’s said to be a girl; if it swings back and forth, it’s believed to be a boy.

Hair Growth

Some believe that if your hair grows faster during pregnancy, you’re having a boy, while slower hair growth indicates a girl.

Garlic Test

The tale goes that if a pregnant woman eats garlic and the smell seeps out of her pores, she’s carrying a boy. If there’s no garlic smell, it’s a girl.

These tales are generally fun to explore but lack scientific backing. For accurate gender determination, it’s advisable to rely on medical methods and consult with healthcare professionals.

While the allure of predicting a baby’s gender has led to the development of various theories and methods over time, it’s crucial for expectant parents to acknowledge the speculative nature of these methods. For accurate gender determination, medically endorsed methods such as anatomy ultrasounds performed in the second trimester or genetic testing are recommended.

Other Tests & Scans

Cell-free DNA testing

One of the most popular and accurate methods of baby gender prediction is known as cell-free DNA testing. This test analyzes small fetal DNA fragments present in the mother’s bloodstream. These fragments are then analyzed to determine the sex of the baby with a high degree of accuracy. This test can be performed as early as 10 weeks into pregnancy and has a reported accuracy rate of over 99%.

Amniocentesis test

Another test is the Amniocentesis test, which is a procedure that involves removing a small sample of amniotic fluid from the uterus. The fluid contains cells from the developing fetus that can be analyzed to determine the sex of the baby. This test is typically performed during the second trimester of pregnancy and has a reported accuracy rate of over 99%.

In conclusion, it is advisable for expecting parents to choose a reliable and accurate baby gender prediction test to know the sex of their baby in advance. It will help them prepare for their new baby’s arrival and take important decisions related to the baby. These tests are now readily available and accurate, so parents can confidently go for them.

lady lying down looking up at an ultrasound machine whilst she has her babys gender determined



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