- FAIRFAX, Va. (AP) -- Fertility researchers say they are successfully
helping prospective parents fulfill their dreams in selecting whether to
have a baby Michelle or a baby Michael.
- The technique involves identifying and
separating sperm cells that carry the Y chromosome, which produces males,
from those that carry the female-producing X chromosome.
- Dr. Edward Fugger of the Genetics &
IVF Institute said Wednesday that sperm cells can be segregated by the
amount of DNA they contain before being used to fertilize an egg through
- The institute's research is published
in the September edition of the journal Human Reproduction.
- The Y-chromosome sperm has about 2.8
percent less genetic material than sperm with the X chromosome.
- Researchers were able to sift sperm to
produce samples in which 85 percent of the cells had an X chromosome. If
they targeted Y-bearing sperm, the result was a sperm sample in which 65
percent of the cells contained a Y chromosome, The New York Times reported
- The institute said 29 women who wanted
to have girls became pregnant. So far, nine of those women have given birth
to 11 healthy baby girls, including two sets of twins, the institute said.
The oldest girl is 2 1/2 years old.
- One of the women still pregnant is carrying
a boy, Fugger said.
- A study of couples wanting boys produced
results consistent with what the sperm sorting would predict, Fugger said.
Exact results were not released.
- Dr. Jamie Grifo, director of reproductive
endocrinology at New York University Medical School, is apprehensive about
the way the institute is using the sperm-sorting method.
- Grifo has been using an entirely different
technique to choose the gender of an embryo since 1992 and said NYU applies
the technology only to prevent gender-based diseases such as hemophilia
and Duchenne muscular dystrophy, which only appear in males.
- "They're doing very important research
but it's a matter of what they're using it for that worries me," Grifo
said. "I don't think we should be doing sex selection."
- Fugger said the institute's technique
can be used to prevent gender-based disease and was unapologetic about
giving families the option of choosing their child's gender.
- "It tends to balance sex ratios
in families," Fugger said. "There shouldn't be an ethical issue
with skewing ratios or anything like that."
- Another outside observer, Dr. Robert
Stillman, medical director of Shady Grove Fertility Centers, in Washington,
D.C., said the institute's research sample is too small to declare success.
- "It's really a series of anecdotes,"
said Stillman, a board member of the American Society for Reproductive
Medicine. "A bigger study might put this in the wastebasket where
many other attempts at sex selection have gone."
- The institute's researchers refined techniques
developed for sorting the sperm of farm animals. Fugger said that of the
more than 400 animals in five different species born through sperm sifting,
none was born with defects.
- The technique involves staining sperm
cells' DNA with a fluorescent dye and then shining laser light on the cells
to make the dye glow. The amount of fluorescent light produced indicates
the amount of DNA present in each cell.
- Dr. Barry Zirkin of Johns Hopkins University
told the Times he was not convinced about the safety of using laser light.
And like Grifo, he also questioned the ethical implications of tinkering
- When it comes to sex selection, he said,
"most people feel this is tampering with nature."