Preimplantation genetic diagnosis (PGD) makes gender selection possible – and is causing some parents to rethink how nature works
Parents used to decide if they wanted to know the sex of the child the mother is carrying, but now technological advances have upped the game by giving parents the option of selecting the sex of their child before pregnancy. It’s called sex selection (sometimes referred to as gender selection) and is possible by evaluating the genetic makeup of embryos formed in the lab to be implanted in the woman’s womb.
We get a lot of inquiries regarding sex selection at TRM. So what exactly is it?
The genetics of sex selection
Sex selection involves evaluating the genetic qualities of an embryo(s) created using IVF and choosing which one to implant in the woman’s uterus for a pregnancy – based on the sex of the child desired by the parents.
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While the desire to choose a baby boy or a baby girl has been present throughout human history, only recently has technology emerged that makes this clinically possible before birth. With improvements in reproductive technology, demand for gender selection has also been growing at a rapid rate.
To understand sex selection, one needs to understand how sex is determined in embryos and, ultimately, babies. All eggs a woman produces are inherently “female” in that they can only contribute an X (female) chromosome to a baby. The male sperm can contribute an X or a Y (male) chromosome.
Ideally, by sorting out sperm that do not carry the Y chromosome one could select sperm for use in artificial insemination and IVF. This is what many couples who come to see us would like us to do. But citing a lack of health benefit, the Food and Drug Administration (FDA) has banned this method in the United States.
Many couples are disappointed to learn that sperm sorting is not an option. Currently there are no techniques other than IVF with PGD that allow for the ability to select one gender over another.
How PGD works
When I sit down with a couple considering sex selection, I explain to them the entire genetic testing process and ask them to consider what they would do in various situations. I explain the IVF process, embryo growth and how we remove a few cells from each embryo for evaluation. A genetic test can then tell us if the embryo has the correct number of chromosomes and whether it is a girl (XX) or a boy (XY).
Success with IVF and sex selection depends greatly on the number of eggs we can obtain from a woman and her age. As a principle, the older a woman gets, the fewer eggs she’s likely to produce; there is also a greater chance that her embryos will contain genetic abnormalities. This means that we need to test to see how many eggs we will likely obtain.
To understand this better, let’s look at a couple of scenarios:
- Scenario 1. A 35-year-old woman wants a female baby. If her pre-IVF testing is favorable, she will likely produce 16 to 20 eggs and out of those we can assume that about four to five genetically normal embryos would be created, half of them likely being female. Each one of those female embryos now has about a 75 percent chance of resulting in a pregnancy. This woman is likely to walk away from all of this with a little girl.
- Scenario 2. A 40-year-old woman has testing that indicates that she would likely only produce four eggs with IVF. Not all of those would successfully fertilize. Only about 1 in 12 of her embryos would be expected to be genetically normal, and only half of those would be the sex she was selecting. All of this translates to a 10 percent chance of getting pregnant with the gender of her choosing.
Why some IVF patients prefer sex selection
People generally have three common motivations for choosing sex selection:
- Medical. Some couples choose gender selection to prevent the birth of children affected by, or at risk for, certain genetic disorders. As with muscular dystrophy, certain genetic disorders are more likely to affect boys, so this testing is more often used to select a female or an unaffected male.
- Family balancing. Most couples are interested in sex selection for non-medical reasons. This is especially true of couples who have children all of the same sex. Sometimes couples that are not infertile want to know what they can do to balance their family.
- Genetic issues. Sometimes couples that already need IVF are using PGD to decrease the chance of miscarriage by screening for a suspected genetic abnormality. While doing that, they also want to be informed of the embryos’ sex.
Ethical issues raised by sex selection
Sex selection for non-medical reasons raises ethical, legal and social issues. The main concerns are that the practice of gender selection will:
- Change the natural sex ratio of children born in favor of males, leading to a gender imbalance.
- Support discriminatory and sexist stereotypes toward women by devaluing females.
In some countries, such as India and China, it is commonly known that the practice of sex-selective abortion has resulted in alterations of the natural sex ratio, in favor of males.
In deciding on whether or not to pursue sex selection, patients must consider the following.
What to do with the embryos that are not the desired sex?
Does the woman/couple discard them? Donate them? Use them later? As physicians, we do not want to place patients in situations where they don’t have good options acceptable to them. And this issue of discarding embryos is apt to be problematic for many people. If we think you are likely to end up in a situation like this, we will tell you in unambiguous terms.
What if the only normal embryos produced are an unwanted gender?
Would the woman go through IVF a second time, hoping for a different result? Or would she go ahead and use the embryos of the un-preferred sex? If so, she probably wouldn’t need to try sex selection in the first place.
What if the woman has a miscarriage?
While not every patient reacts the same way to this situation, in my experience the couples that have miscarriages after choosing sex selection, on average, have a much harder time dealing with the loss of the pregnancy. I’m not exactly sure why this is. But it’s something I’ve noticed and I warn my patients about it.
Final step in sex selection
Sex selection is a complex issue, requiring careful evaluation. After considering all the issues and possible outcomes covered above, make sure you and your family are comfortable taking the big step of sex selection. Many couples overlook the need to involve their family members.
Whether one chooses sex for medical or personal reasons, it’s important to fully consider and evaluate all outcomes. Prior to deciding if it is right for you, have a conversation with me or Dr. Jessica Scotchie.
We’re happy to spend time discussing any or all of these issues with you. And if a fertility provider is not willing to address these thorny issues with you head on, you should probably find one who will.