Few issues in reproductive medicine are as controversial as gender selection. As the father of children of both genders I can certainly understand the desire for family balancing. However, few concepts are as disturbing as abortions performed on the basis of fetal gender alone. After my two sons were born, we figured that we would probably only have boys if we continued to add to our family. Then came pregnancy #3 and after a bunch of ultrasounds performed by yours truly, I was pretty sure that there was a change in the wind and we were having a girl. We confirmed this at 18 weeks with an anatomy sonogram and Leah was born in December 1997 (in New York to boot which made it hard on me given my Boston roots). To this day she loves to call herself a New Yorker, for reasons that are beyond me.
In any case, although the “Question of the Day” could be “Why are the Red Sox losing so many games?” I will keep to the subject at hand as we discuss gender selection.
17. Can I choose the sex of my baby?
Gender is determined at the moment of fertilization, when a sperm bearing either an X or Y chromosome penetrates the egg, resulting in formation of either a female or male embryo, respectively. The event is random, and the sex ratio of females to males conceived is fairly even. Several techniques exist that can enhance the likelihood that a couple will conceive a child with the desired gender. The Ericsson method is a simple, noninvasive method that separates X-bearing sperm from Y-bearing sperm using centrifugation techniques. The sperm are placed on the top of a column of either albumin or Sephadex, and the specimen is centrifuged to isolate the desired gender-selected sperm. These sperm are then placed in the female partner through in-office artificial insemination. The success rates reported with this method vary from no benefit to as high as 75% for the desired gender. The Ericsson method is not associated with any known risk to either baby or mother.
A newer experimental technique (Microsort) involves the labeling of the DNA of the sperm, followed by passage of the sample through a cell-sorting machine. This process yields a smaller sperm sample than the Ericsson method, and IVF with ICSI may be required for pregnancy. Nevertheless, the results appear encouraging in terms of gender selection. The gender of a child can also be selected using IVF and preimplantation genetic diagnosis (PGD). This technique is expensive and much more complex than the Ericsson method, but success rates for the selected gender routinely exceed 90%. Couples who elect to pursue IVF and PGD for gender selection often do so to prevent genetically inheritable medical diseases, such as Duchenne muscular dystrophy, from occur- ring in their children.
Many medical authorities consider gender selection to be unethical except in a few circumstances, such as when the couple runs a high risk of having a child with an inheritable medical disease. Gender selection may also be used when a couple has at least one child but want to limit their family size and desire a child of the opposite gender.
lundi 2 juillet 2007
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