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Understanding Family Balancing

Family balancing refers to the use of preimplantation genetic testing for aneuploidy (PGT-A) to identify the sex of embryos created using IVF and then transferring only embryos of the preferred sex. It is sometimes called sex selection or gender selection and it is used in a relatively small percentage of all IVF cycles.

While this genetic testing is intended to check that an embryo has the correct number of chromosomes before transfer, a practice that improves pregnancy outcomes, the same test also opens the door to family balancing.

WHAT IS FAMILY BALANCING?

Family balancing is the use of assistive reproductive technologies to “balance” a family through sex selection.

Family balancing can be a nonmedical decision, such as if a couple wants to have a females to round out their family of males, or medically driven, like if a person has or carries a genetic disorder that is more likely to affect offspring of a specific sex.

It should be mentioned that today, there is a separate genetic test for IVF embryos that looks for specific, single gene mutations like those causing many sex-linked genetic disorders. This genetic test (PGT-M) has made it possible to exclude embryos that are affected by a sex-linked genetic disorder without excluding all embryos of that sex.

How is sex selection possible?

The sex of a baby is determined by two chromosomes called sex chromosomes. Eggs carry an X chromosome, while sperm carries either an X or a Y chromosome. If a Y-chromosome sperm fertilizes the egg, the embryo is male (XY). If an X-chromosome sperm fertilizes the egg, the embryo is female (XX).

A genetic test can look at the chromosomes of any embryo created using IVF to see whether the embryo is male or female. Using this information, the family can choose to transfer an embryo that is of their preferred gender.

What is the process for family balancing?

The procedure for sex selection begins with conventional IVF. As the embryos are growing in their incubators, a few cells are biopsied from each embryo around day 5 of development and genetically tested using preimplantation genetic testing (PGT-A). This genetic test looks at the full set of 23 pairs of chromosomes and can tell by looking at the sex chromosomes whether there are two X chromosomes (indicating a female embryo) or one X and one Y chromosome (indicating a male embryo).

A fresh or frozen embryo transfer will follow, with the embryo(s) of the desired sex are being transferred to the uterus. Any remaining healthy embryos can be frozen for possible future use.

What are some of the problems with family balancing?

While the idea of selecting the sex of your unborn child is controversial to some, there are families that have a strong desire to add either a female or male to their family. This might be amplified in families that already have multiple children, or those that only plan to have one child.

If this choice is not medically necessary, then patients most likely will have to self-pay for their IVF, genetic testing, and all other associated costs. You would also want to take into consideration the risks of treatment without medical necessity. There is also a small risk that the diagnostic testing could be incorrect.