Putting
the Freeze on Infertility
by Corey
Senn |
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Back
in 1997, Carol and Don Terry of Atlanta were experiencing difficulty
having children. When they underwent in vitro fertilization,
their greatest hope was that one of the four fertilized embryos
would grow into a beautiful baby. Imagine their surprise when
Carol's infertility specialist announced that she was pregnant
with FIVE, -- count 'em, five -- babies (one of the embryos
had split into identical twins). Since
the introduction of in vitro fertilization (IVF) in the U.S.
in 1981, there has been a steady rise in the number of multiple
births. According to abcNEWS.com, "two-thirds (of the total
increase) of multiple births are due to fertility treatments."
In addition to the obvious difficulties brought about by the
birth of several same-age children, multiple births also have
a much higher infant mortality rate, as well as an increased
risk for long-term illness and disability. Given these potentially
serious complications, many IVF clinics have focused on ensuring
that embryo freezing is both a safe and efficient way to minimize
multiple births, as well as a way to give couples more choice
in their family planning.
IVF
Explained
Embryo
freezing is typically used in conjunction with a normal IVF
cycle. A woman is first prescribed fertility drugs in
order to stimulate multiple egg production in her ovaries. Once
ready, she visits her clinic, where the infertility specialist
removes an average of 12-15 eggs.From
here, the eggs are joined with the sperm in the laboratory.
The successfully fertilized eggs are then either reinserted
or frozen. Most fertility clinics initially reinsert two of
the healthiest embryos into the woman's uterus. The process
is no more painful than a pap smear.
Freezing
the Embryos
The
remainder of the healthy, fertilized embryos are frozen using
what's called a "Computerized Programmed Freeze." According
to Michael Darder, MD, Co-Director of IVF New Jersey and former
medical director of Columbia University's IVF program, "the
programmed freeze drops the temperature of the embryos at
certain rates. They are then stored in a liquid nitrogen tank
where they can be suspended indefinitely."
In
the last year, there has been a move towards allowing embryos
to develop into blastocysts (an embryo 5 days after fertilization)
before they are frozen. "This enables the doctor to pick out
the best embryos," explains Dr. Darder. "Less of
the embryos reach the blastocyst stage, but those that do
are of better quality." About half of the women who go through
the New Jersey IVF program will have enough embryos to freeze.
Often, four or five embryos can be frozen, although there
will usually be fewer blastocysts.
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Embryo
freezing reduces the chance of multiple births and gives
couples more latitude in their family planning
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The
most important benefit of embryo freezing: it reduces the
chance of multiple births. "Some patients think we have to
put back a bunch of embryos in order to maximize the pregnancy,"
says Eldon Schriock, MD, of the Pacific Fertility Center in
San Francisco. "But when that's done you end up with
quadruplets. With an excellent freezing program, it takes
that fear away. They know they can put two embryos back and
freeze the other two and the chances (of pregnancy) really
aren't going to change." Obviously, reinserting two embryos,
as opposed to four or five, greatly reduces the chance of
multiple births. A woman may still have twins--often considered
a happy prospect--but avoids, for instance, quintuplets, which
would test the stamina and mettle of even the most devoted
parents.
Embryo
freezing also allows couples to have more latitude in their
family planning. A single IVF cycle can provide enough embryos
to achieve pregnancy this year, and in future years. After
the initial attempt at IVF, a woman can return in subsequent
years and use the frozen embryos to become pregnant with another
child. "One of our IVF patients got three separate pregnancies
over a five-year period. The first was from a fresh embryo,
and the next two were from frozen embryos," notes Dr. Schriock.
Additional
Freezing Alternatives
Two
other freezing methods to be aware of:
·
Sperm freezing for IVF is usually used as a
backup. In most cases, the clinic stores the man's sperm in
case he is unavailable when the eggs are ready to be fertilized.
Sperm freezing is also ideal for men who have cancer or Hodgkin's
disease and wish to preserve their healthy sperm to start
a family in the future.
·
Freezing unfertilized eggs has not yet been
perfected, mainly due to the fragility of the chromosomes.
Many fertility specialists feel egg freezing is a year away
from being a viable option. It will eventually allow women
to freeze their healthy eggs and then have them fertilized
once they have found a partner and are ready to start a family.
Egg freezing is also ideal for women with serious illnesses
and for those who are unable to undergo the IVF process.
It's
no surprise that embryo freezing has become extremely popular.
"Last year, roughly half the babies in our program came from
frozen embryos," notes Dr. Schriock.
And
the cost? According to Debra Crawford of the American Society
for Reproductive Medicine, an IVF cycle can range from $8000
- $12,000. Whatever the price tag, though, IVF and embryo
freezing can bring couples the greatest gift of all - a happy,
healthy family.
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