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How Does Gender Selection Work?

Posted on June 1, 2020

Throughout most of human history, expectant individuals and couples had to wait until a baby was born to know whether they were having a boy or a girl. As medical care became more technologically advanced, prospective parents were able to learn of their child’s sex during an ultrasound or specific early testing. Today, technology has taken the science of sex another step further with gender selection.

Gender or sex selection is a medical procedure in which prospective parents undergoing intrauterine insemination (IUI) or in vitro fertilization (IVF) choose the sex of their child. There are several reasons why parents might choose this option, including the desire to have a balance of genders in the family. Another common reason to pursue gender selection is to prevent genetic and chromosomal abnormalities that are gender-specific.

How Sex Is Determined in Traditional Conception

When embryos are formed, the egg provides all of the female’s genetic material, including an X chromosome. The sperm provides the genetic material from the male, including either an X or a Y chromosome. Thus, it is the sperm that determines what the sex of the child will be. If the sperm has an X chromosome, the resulting fetus will be a girl; if the sperm carries a Y chromosome, the fetus will be a boy.

How Sex Is Determined With Gender Selection

There are a few ways in which sex can be selected. One way is through a process known as preimplantation genetic screening (PGS), which is a procedure in which lab-cultivated embryos are screened for genetics prior to implantation into the uterus. This process is used only in IVF and is commonly used to weed out embryos that have genetic abnormalities, but it can also be used for gender selection.

Another method for gender selection is known as the Ericsson Method, which hinges on the idea that Y chromosome sperm swim faster than X-chromosome sperm. In this process, a fresh semen sample is taken to a laboratory and spun in a centrifuge to separate the sperm from the seminal fluid. The sperm swim through a sticky protein liquid known as albumin. The process is repeated and, by the end of the process, there is a sample of concentrated sperm that has a higher percentage of Y chromosome or X chromosome sperm, depending on your gender selection.

The final sperm sample is then used in IUI. It’s important to note that, unlike PGS, the Ericsson Method and other similar techniques only increase the odds of conceiving a specific gender – this method is generally successful for 70%-72% of male sex selection and 69%-75% of female sex selection.

Learn More

To learn more about gender selection and to see whether it’s a good option for your fertility care needs, please contact the Fertility Center of California.

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