Melbourne
SOME fertility clinics are achieving such high success rates for IVF that the
women they treat now have a better chance of getting pregnant in one cycle than
fertile couples relying on plain old-fashioned sex.
The latest to announce soaring pregnancy rates is a small country clinic in
Australia. Reproductive Medicine Albury in New South Wales has consistently
achieved a pregnancy rate of 36 per cent per IVF cycle since it tightened up
temperature control of eggs and embryos four months ago.
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This is far better than the Australian average for IVF of 21 per cent in
2000—the latest figures available—and twice as good as the clinic’s
own pregnancy rates before the changes. Some clinics in Britain and the US now
have birth rates as high as 40 per cent.
The figures would be even higher if they didn’t include couples with
fertility problems for which IVF won’t work no matter how many times they try
(91av, 12 January, p 12).
By comparison, couples with no known
fertility problems having sex have only a 25 per cent chance of pregnancy each
month, though of course in the long run most succeed.
IVF figures are always controversial, because competition between clinics is
fierce and there are many ways to massage the figures—for instance, unlike
Albury, by quoting very early pregnancy rates, many of which don’t result in the
birth of a baby. Nonetheless, there’s been “a quantum leap” in routine IVF
pregnancy rates, says Keith Harrison of the Queensland Fertility Group in
Brisbane. In Britain, where success rates tend to be higher, there’s been a less
dramatic but steady rise, says Sue Avery, scientific director at the Bourn Hall
Clinic in Cambridge, where IVF was first developed.
The reasons for the improvements are not entirely clear. At least part of the
change, however, is being put down to tighter controls on temperature and
pH, better growth media and other improvements in lab conditions.
For example, when eggs and embryos are being manipulated during IVF the dish
is usually placed on a warm platform to maintain body temperature. But as heat
is lost from the top of the dish, the temperature can drop a few degrees. The
Albury clinic solved this problem by blowing warm air over the dishes.
There is a downside to the increased success rates. More women are having
twins and triplets—in Albury, half the women are having twins. As multiple
pregnancies tend to involve more complications, clinics are now considering
implanting only one embryo in some women.
The latest results are not yet included in official statistics, which lag
several years behind. “But there’s now substantial evidence that the good
results achieved by these tweaks can be duplicated,” Harrison says. “All clinics
should be adopting them.”
While IVF may now be the fastest way to get pregnant, for most couples it’s
likely to remain the last resort. “IVF is expensive and intrusive,” Harrison
points out. “People are going to continue getting pregnant by bonking in the
suburbs rather than coming to us.