Male or female: ways to find out the sex of the fetus

History tells us of many parents who, without waiting for the birth of their child, waved crystals on the mother, consulted the stars or measured the heart rate of the fetus, to find out if it would be male or female. Who has more, more. With the only possible rational conclusion: the chances that a boy (or a girl) will arrive are about 50%. Obviously, today there are more accurate ways and techniques to determine the sex of the unborn child before its birth.

When you can know

If you are at least 12 weeks pregnant, a doctor will be able to tell you with a high degree of certainty what the gender of your baby is by means of a medical diagnostic investigation through an ultrasound (or echotomography).

Of course, as long as you’re really interested in knowing right away.

Many parents look forward to having this ultrasound because they want to choose a name or stock up on baby clothes before the big day.

By means of an ultrasound, doctors not only get to see an image of the baby, but also have a good chance of finding out its gender: boy or girl.

Doctors use ultrasound – before, in early pregnancy – both to measure the size of a fetus and to check the baby for defects or other problems, not to check the its sex which in this first phase is not yet distinguishable.

Most babies, around the twelfth week of pregnancy, have distinctly male or female genitalia. If the fetus were to “collaborate” being in the correct position, this ultrasound “of the 12th week” will allow a good view of its sexual organs.

As for the degree of precision of the measurements regarding the sex of the future child, according to a study published in Ultrasound Obstetrics and Gynecology, an ultrasound,

  1. at 11 weeks, it is 70% accurate;
  2. at week 12, it is 99% accurate.
  3. At the thirteenth week, the baby’s image is absolutely clear and, if the baby “cooperates”, the ultrasounds (on which the ultrasound is based) are able to show us clearly whether it is a boy or a girl.

Ask the doctor who is doing this ultrasound for you if they can get a clear, unobstructed view of your baby’s genitals.

  • If your doctor is clear about the sex of the fetus, you can be sure of what they tell you.
  • If not, you may have to wait for a subsequent ultrasound (or find out on the day of delivery).

Amniocentesis and CVS

All those tests that involve taking a genetic sample can determine the sex of the unborn child with near-perfect accuracy. Doctors usually use

  • of amniocentesis,  a method for prenatal diagnosis through biological samples,
  • chorionic villus sampling, a method that is performed by taking chorionic villi: it is an invasive test useful for diagnosing chromosomal or genetic anomalies.

It should also be said that, at times, these tests can also cause a  miscarriage : in fact, a 2006 study found that this risk occurs 1 time out of 370 cases.

For this reason, the doctor does not use these tests only to see if the future child will be a boy or a girl. However, if for any other reason he is doing these tests, and you are interested in knowing the sex of your baby, it is time to ask him.

And then, of course, you also have the other option: to wait for the baby. When you finally have that little bundle in your arms, you’ll know everything you need to know.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform,

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