Sex Pre-selection

The sex of a child is determined by the particular sperm fertilizing the egg: sperm cells carrying an X chromosome result in a female and those carrying a Y chromosome result in a male. Semen contains approximately 50% female and 50% male sperm cells. People have tried to change the sex ratio of children for millennia but the natural balance of 50:50 is not readily altered. Most of the older techniques for sperm selection, including albumin and density gradient centrifugation, have never been scientifically validated by reliable studies. The only technique which has been rigorously studied and found to be effective is flow cytometry patented as MicroSort®. The MicroSort technology is based on the fact that the X chromosome is slightly larger than the Y chromosome. This difference in DNA content can be measured and used to separate the X- and Y-bearing sperm cells.

MicroSort sperm pre-selection works better for X-bearing sperm than for Y-bearing sperm. The technique has resulted in births of about 94% females with sorting for X-bearing sperm compared to only about 74% males with sorting for Y-bearing sperm. Currently only two locations offer MicroSort sperm processing, one laboratory is in Virginia and one in Southern California. Therefore, couples residing in Northern California usually require freezing of sorted sperm in preparation for ICSI-IVF treatment at Alta Bates. As a result, the combined procedure is costly (approximately $17,000 per attempt) and there is no assurance that either a live birth or a child of desired gender will be achieved.

Patients who desire to use MicroSort for family balancing must have at least one child and sort for the less represented sex of children in the family. Therefore, MicroSort is not currently available for pre-selecting the sex of the first child. In addition, the woman providing the eggs must be under 39 years of age. For further qualifying criteria and other information, please consult the MicroSort website (http://microsort.net) or contact one of the MicroSort facilities by calling 1-866-472-4483 or 1-800-277-6607.