By Sara Salgado BSc, MSc (embryologist).
Last Update: 02/22/2016

Many couples consider predicting the gender of their unborn baby an advantage, since this way they can start arranging things for the baby’s arrival, such as picking a name, getting nursery decorating ideas…

Prior to the development of a scientific method for determining the sex of an unborn child, early cultures had already created a series of “old-wives” tales to do so.

Nowadays, technological advancements such as ultrasound scanning are among the most used ways to find out a baby’s gender, though some cultures have continued to use historical ways to tell the sex of babies.

Historical baby gender predictors

There exist various myths on how to predict a baby’s gender. Since none of them have yet been scientifically proven, they have a 50/50 chance of success.

Some tales are related to the pregnant woman, among which we can find the following:

  • The belly test: Having a pointed belly shape during pregnancy means your baby’s gender is a boy. On the other hand, a round belly shape means your baby’s gender is a girl.
  • The oil test: When pouring a few drops of oil on the belly, if it drips rapidly, then it is a boy. If it drips slowly, you are pregnant with a girl.
  • Cravings: If the pregnant woman craves sweets, she is expecting a girl; on the other hand, if she has a preference for savory or citrus foods, she is pregnant with a boy.
  • Dream intuitions: If circles appear on the woman’s dreams, she is expecting a girl, whereas it is a boy if pointy objects show up.

Others believe that different aspects related to the conception date have an influence on the unborn child’s sex. For instance, the day of conception being odd or even determines the baby’s sex. For others, the gender is based on moon phases.

The so-called Chinese Gender Predictor is a calendar according to which the baby’s sex depends on the age of the pregnant woman in the very moment she got pregnant and the month of conception.

Some couples have a preference for the ovulation calendar, which is commonly used for either predicting the baby’s gender and trying to do so once the woman has fallen pregnant.

According to this method, spermatozoa Y (from which a male will be born) are faster swimmers than spermatozoa X (from which a female will be born), although their survival capacity is more limited.

Keeping this in mind, chances of having a boy might be higher if you have intercourse while the woman is ovulating. On the contrary, for your baby to be a girl, you should engage into sexual activity 2 or 3 days prior to her ovulation days.

At-home gender prediction test

Nowadays, there exists a gender prediction kit that uses urine to check for the gender of the unborn child, which accuracy reaches 90%.

It is a kit that can be purchased without a prescription on week 10 of pregnancy. Results are shown in a few minutes.

However, this tool is unreliable both in cases of multiple births or if the woman is taking hormonal therapy medicines such as progesterone.

Baby gender blood test

This type of blood tests allow you to determine your unborn child’s gender as early as on week 8 of pregnancy.

The blood sample will be genetically analyzed in the laboratory with the purpose of examining the presence of the Y chromosome, this way allowing for the determination of whether it is a boy or not.

Sonogram

Determining your baby’s gender through a sonogram or ultrasound scan is the less invasive, safest and most common way of doing so. It can be done when the woman is 13 weeks pregnant onwards, although chances for the result to be accurate are higher if performed from week 16 onwards.

In order to determine the gender, the genitalia of the fetus is examined. If there is the presence of some protuberance, we can suspect it is a penis and therefore our unborn child is a boy.

However, there are times when the position of the fetus in the womb makes it difficult for his genitalia to be seen. Besides, in case it were a girl, distinguishing it through ultrasound scan becomes harder.

Amniocentesis

It stands for an invasive test used to determine the presence of some genetic abnormality in the fetus. With an amnio test, the baby’s sex can be determined, since a chromosome analysis is conducted too. Nonetheless, given that both the fetus and the pregnancy itself are put at risk with this test, it cannot be used only with the purpose of finding out whether you are pregnant with a boy or a girl.

Firstly, a sonogram is performed to determine the position of the fetus in the uterus. Then, a thin needle is inserted through the navel in order to remove a sample containing fetal DNA.

This procedure can be performed from week 15 of pregnancy onwards.

Authors and contributors

 Sara Salgado
BSc, MSc
Embryologist
Degree in Biochemistry and Molecular Biology from the University of the Basque Country (UPV/EHU). Master's Degree in Human Assisted Reproduction from the Complutense University of Madrid (UCM). Certificate of University Expert in Genetic Diagnosis Techniques from the University of Valencia (UV). More information

2 comments

    1. virginia hiddleston

      Hi, wondering if anyone has had like a gut feeling about their baby’s gender. I already have 2 boys, and this time my pregnancy is going exactly the same as my 2 previous ones… That’s why I’m guessing I’m pregnant with another boy, which I find fantastic 🙂 Is a mommy’s instinct usually accurate?

      • Sandra FernándezBA, MA

        Dear virginia,

        As stated here, this kind of methods have not been scientifically proven yet, so you have a 50/50 chance of being right.

        Hope everything goes wonderfully 🙂

        Regards