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A common question from parents: "How can I influence whether or not I have a boy or girl?" I usually laugh and respond that if I knew the answer to that question, I wouldn't have had two boys. All joking aside, parents have been trying to influence the sex of their baby at conception for as long as people have been trying to make babies. Some couples want to avoid passing a gender-linked genetic disease to their child, while others just want to shift the odds in favor of the opposite sex to balance their families. There have been myths regarding gender selection and books written on the subject. Despite all the hocus-pocus, there has been legitimate scientific research in this field. Read on to learn what I found out by interviewing Dr. Mark Kan, a specialist in reproductive endocrinology and infertility. Here are the truths behind the mysteries of gender selection. How is the gender of a baby determined? The sex of a baby is determined by the two sex chromosomes inherited from the parents. A baby will normally inherit one sex chromosome from the mother and one from the father. Since the egg already contains an X chromosome (from the mother), the gender of a baby is determined by the X or Y sex chromosome of the sperm cell from the father. Yes, we can blame the man once again! The sperm determine the sex of the child. Therefore, a girl baby will result if the final arrangement is XX, and a boy baby will result if it is XY. Natural semen contains approximately equal numbers of female- and male-producing sperm. Realizing that gender is dependent on the X-bearing and Y-bearing sperm cells, scientists have attempted for years to separate these two populations from each other. Dr. Kan explains that sex selection procedures are based on theoretical and actual differences between the two types of sperm cells. How can you tell X sperm from Y sperm? Various methods attempting separation have included: spinning the cells to separate them by weight, having the cells swim through different layers of media, or placing the cells in an electric field, along with countless other procedures. While there have been reports that some of these techniques have separated X and Y cells to various degrees, it has been difficult to reproduce any clinically significant success. What works best The most successful technique to date is a process called flow cytometry. This involves staining the nuclear material of the cells with a dye and then passing the cells through a machine in a high-speed, single-file line. The cells are then separated based on the amount of DNA stain that is read by the machine. The X chromosome is larger, thus emitting more signal because it takes up more stain. This technology is called Microsort, and has been utilized as part of an FDA clinical trial for preconception gender selection. A lab in Orange County is one of only two in the country where this process is currently available. A couple with a history of an X-linked disease, where the woman is a known carrier, may qualify for free treatment with Microsort. Examples of such disorders include hemophilia and Duchenne muscular dystrophy. For families who want to use Microsort for sex selection, the couple must be married, the wife must be between ages 18 and 39, and they must have at least one child and be selecting for the less represented gender of children in their family. Currently, Microsort sperm-sorting technology improves the chances of a female pregnancy by 89.5 percent, and for a male by 73.6 percent. Dr. Kan cautions, however, that it is important to know that this technique requires DNA staining with a fluorochrome (a fluorescent dye) in addition to ultraviolet laser exposure. The long-term consequences of this procedure are not known. However, animal and human studies have not shown an increased rate of birth defects over what is expected in the general population so far. While attempts have been made over the years to select the gender of a child before conception, there is currently no process that can guarantee the selection of either a boy or a girl. For many couples, the ability to simply have a healthy baby is reward enough. For reproductive endocrinology and infertility questions, Dr. Mark Kan can be reached at 949.389.1920. For more information on Microsort, you can contact the Huntington Reproductive Center in Laguna Hills, or view their website at www.microsort.com. Dr. Lisa M. Karamardian is a board-certified OB/GYN and Fellow of the American College of Obstetricians and Gynecologists. A frequent speaker in the community, she also serves as medical advisor for Contemporary Nutrition. She lives in Newport Beach with her husband and two sons, |
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