While some parents welcome the idea of nature choosing their baby’s gender, others have their hearts set on a pink or blue bundle and want to stack the odds in their favor. But is it possible to sway the process of sex determination one way or the other?
A quick look online will guide you toward “gender calendars,” which encourage sex on certain days depending on whether you want a boy or girl, or even suggest certain sexual positions for achieving the kid of your dreams. But the truth is, other than IVF, in which a sample of the embryos’ cells can be identified as containing either XX (female) or XY (male) chromosomes and then implanted according to the parents’ preference, there is no guaranteed method for choosing the sex of your child.
So what does sperm sorting offer? Well, hope. While these doctor-assisted techniques aren’t guaranteed – indeed, some fertility doctors don’t believe that they give couples any more than a 50/50 shot at the desired sex – they are actually based on biological processes, and the clinics that offer them claim they work, allowing parents to feel like they are taking an active role in the gender process.
The basics of sperm sorting: All of the techniques to sort sperm rely on the fact that those carrying an X chromosome and those carrying a Y chromosome have different physical properties. Sperm are said to be sorted by X and Y, and the desired sperm are delivered to the uterus either by artificial insemination or in vitro fertilization.
Sperm spinning involves spinning a sample of semen in a centrifuge. The slightly heavier sperm containing an X chromosome are separated from the lighter Y-containing sperm. Here are two examples of some of the popular variations on sperm spinning:
MicroSort is a technique developed by a private company, the Genetics & IVF Institute, that is currently in clinical trial (meaning it’s not approved by the FDA). The method uses “flow cytometry” and relies on the fact that the X chromosome is significantly larger than the Y, and so X-bearing sperm have slightly more DNA overall. The sperm are separated based on this fact and then dyed to confirm they’ve been separated. That sample is then transferred to the uterus by artificial insemination or IVF.
The company claims that female sperm sort with an 88 percent accuracy, and males with 74 percent accuracy, and, indeed, there is some data to show the process is more effective than leaving it up to chance. The technique isn’t cheap – starting at around $5,000 for sorting and artificial insemination (which has a modest success rate each time) and going up considerably with IVF (which is more invasive but has a higher chance of resulting in a pregnancy).
The Ericsson method has been around longer and is somewhat less high-tech. This technique separates sperm by capitalizing on the fact that boy sperm tend to swim faster than girls. A semen sample is poured into a viscous fluid, and as the sperm make their way down a test tube, those that reach the bottom first are captured. The desired sex-chromosome-containing sperm are delivered by artificial insemination.
Some doctors who offer the Ericsson method claim it is roughly 70-80 % effective, but many fertility doctors dismiss this method. It’s definitely cheaper than the Microsort option, however, starting at around $600 per try.
The controversy: Sex selection techniques were originally developed to help couples avoid certain sex-linked medical conditions. For example, 50 percent of males born to a woman who carries the gene for hemophilia will have the condition themselves (girls will not), so sex selection helps these women have girls. But as sex selection becomes more widely available, many argue it feeds gender discrimination, especially in societies that value one sex over the other. Professional organizations like the American College of Obstetricians and Gynecologists have expressed concern about the ethical implications of these techniques.
What do you think about the idea of using medical technology to stack the odds of having a baby of one sex over the other?