How New Technologies Can Help Influence Whether You'll Conceive a Boy or a Girl

Upping the Odds

The crudest way of choosing a child's gender is through a "selective abortion." Amniocentesis, the early-pregnancy test that screens for genetic diseases, determines the gender of a fetus, and if it's not the "right" one, the mother can then abort the pregnancy. While this method is reportedly used in some parts of the world, it is not common here, although fertility experts say it isn't unheard of either.

There are three more sophisticated sex-selection methods available to today's moms -- each also involving significant drawbacks and ethical considerations. The oldest was developed in the mid 1970s by geneticist Ronald Ericsson, PhD. This method relies on the fact that the X chromosomes (female) in sperm are larger and denser than the Y chromosomes (male). Sperm is filtered through a human serum, which separates the faster-swimming male sperm from the slower female sperm. Women are then artificially inseminated with the sperm containing a higher ratio of the desired gender. Although this is relatively affordable (at $2,000 per cycle) and is not medically invasive, it fails as often as three out of 10 times.

A more successful method is preimplantation genetic diagnosis (PGD), a test originally developed to screen for sex-linked genetic diseases, such as hemophilia and muscular dystrophy, which disproportionately affect boys. This process can only be done during in vitro fertilization (IVF), in which a woman's eggs are surgically removed from her ovaries and then fertilized with her partner's sperm in a laboratory dish. In a routine IVF procedure, the fertilized embryos are transferred back to the woman's uterus; but with PGD, one or two cells are removed from each embryo. By analyzing these cells, doctors can tell -- with almost 100 percent accuracy -- the boys from the girls. The "preferred" embryos are then used in the IVF process, while the others are either donated to another couple or to research, where they are eventually destroyed. (Many people find the destruction of embryos to be morally reprehensible.)

A newer, more promising technique is MicroSort, a variation on the Ericsson method. Sperm is stained with a special dye and then run through a machine that can distinguish male DNA from female DNA in the sperm and sort out the unwanted gender. Women are then inseminated with sperm carrying the chromosomes of their choice. MicroSort has been in clinical trials since 1993. Initially, those trials were only open to couples with histories of sex-linked diseases, but they quickly expanded to include people who wanted to choose their baby's gender. To date, 86 percent of the nearly 800 couples who've conceived through MicroSort have done so for sex selection.

The process is expensive: Each attempt at fertilization through IVF costs from $15,000 to $20,000. And it's far from foolproof: Sperm sorting has up to a 90 percent success rate at helping women conceive girls, but only a 76 percent rate for boys. Still, if the trials prove the method is safe and effective, MicroSort plans to ask the Food and Drug Administration to approve the procedure. If that happens -- and if some of the newer sex-selection methods currently being researched come to fruition -- picking your child's gender could become as routine as shopping for a luxury car.

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