Human sperm cells carrying a (female) X chromosome have more total DNA than sperm cells with a (male) Y chromosome, making them slightly larger. MicroSort technology uses a flow cytometer to sort sperm by size so that parents can increase their chances of having a child of a particular gender. The success rate for selecting gender is about 80 percent for female babies and 70 percent for male babies. (See also Family Balancing.)

Glossary of Medical Terms