Transcript for Would You Choose the Gender of Your Baby?
Now to a new series we're launching this morning to answer all of your questions about fertility. We're calling it baby boom. Gender selection. A highly controversial topic. Some parents selecting the sex of the child all in the name of family balancing. The big question for every modern family expecting a new baby. Would you like to know if you're having a boy or a girl. Yes. No. I want it to be a surprise. Don't you, jay. Reporter: Now a huge spike in the number of couples choosing the sex of their baby before they even become pregnant. This is the room where the magic begins. Reporter: It's called gender selection. Up to 90% of patients come to this doctor because they want to decide if they have a boy or a girl. Thousands of cases. We have never, ever gotten the wrong gender. The demand has increased almost tenfold in the last ten years. Reporter: It's not without controversy. The United States is only one of a handful of countries that allows the practice. There's nothing diseased or disordered. You're asking for a preference. Will we have people pick traits of their kids down the road? Height? Eye color? Musical aptitude? Sexual orientation? Reporter: Gender selection is a way to guarantee a baby of the opposite sex. We have the option to do that. We would like a girl. Reporter: This couple, who didn't want us to use their names says when they learned about the option of gender selection decided to choose a daughter. I come from a family of all boys. We had a son. I said I would like to have a daughter. And we got two. Reporter: Now they have twin daughters. They haven't ruled out using gender selection again. Are you happy with our decision? Jeff it inially not. Wonderful. Couldn't be happier. And here, Dr. Jennifer Ashton. Let's talk about how doctors go about determining gender. What is the medical science? There's two methods. The first is sperm shorting. Using a high-tech method, the sperm carrying a Y chromosome are separated. The second is pgd, or preimplantation genetic diagnosis. After the embryo is fertilized. It gets to about the five-day stage. Then think of it like a very, very delicate biopsy. Or a superearly am neyo essential tee sis. Part of the cell is removed and tested. Obviously, people do this for gender selection. Others do it for medical reasons. That's how it started. To look for certain medical disorders. Things genetically passed on. Like cystic fry bro sis. Hemophilia. There are over 100 diseases that can be tested for. It can be used if a parent has an existing sick child to work toward a stem cell treatment. Can you break down the pros and cons? The ethical principles. The things that are for this or for nonmedical gender selection. Patient autonomy and reproductive liberty. Those are very individual. That sup to that patient or couple. The things on the opposing side, against this, you're talking about gender discrimination. We have seen that in China and India, where they want a boy child. Or inappropriate use of medical resources. We have to remember, there are risks involved. You have to be okay with getting bad outcomes. Zblz a a doctor, your thoughts? As a doctor and a mom, my motto is stay in your lane. For nonmedical reasons, be surprised. Take what nature gives you. Dr. Jen, we appreciate it. Tweet her at drjashton. Stay in your lane.
This transcript has been automatically generated and may not be 100% accurate.