THE developed world is facing a disastrous 鈥渆pidemic鈥� of twin and triplet
births, scientists warned at a conference last week. They are calling for
radical changes to fertility treatments to prevent a huge increase in problem
pregnancies and birth defects.
Increased use of IVF is one reason for the rise in multiple births. 鈥淭he
incidence of multiple pregnancy after IVF in Britain is about 25 per cent. That
is a real concern,鈥� says fertility expert Robert Winston of Imperial College,
London. 鈥淭he pressures both upon the clinics and on the patients to go as close
to the limits as possible are still undeniably there.鈥�
Multiple births often occur after IVF because doctors transplant more than
one embryo to make a successful pregnancy more likely. Another problem is that
the drugs used to induce ovulation often make ovaries release several eggs at
once. Winston says these drugs are handed out too freely. 鈥淪adly, they are not
regulated in many countries,鈥� he says.
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Multiple pregnancies are a problem for health services because they鈥檙e
plagued by complications. Babies are often premature, underweight and need
expensive intensive treatment, and their mothers need more prenatal and
antenatal care. Multiple births can also lead to neurological disorders, with
triplets being 20 times more likely than singletons to have cerebral palsy.
The epidemic of multiple births arising from fertility treatments escalated
swiftly, experts warn. Between 1980 and 1997, the twin birth rate in the US
increased by 42 per cent, according to Laura Schieve of the Centers for Disease
Control and Prevention in Atlanta, Georgia. Triplet and higher multiple births
increased by 370 per cent. 鈥淚n the US, as elsewhere, there鈥檚 been an alarming
rise in multiple births,鈥� Schieve told the meeting.
If current trends for triplet births continue, says Jaroslaw Oleszczuk of
Polish Mother鈥檚 Memorial Hospital in L贸dz, almost a third of all people
born will be a triplet in some countries within a decade or so. 鈥淚f we don鈥檛
change anything, the rates will increase exponentially as they have done over
the past 20 years,鈥� he says.
In the US, for instance, triplet births could rise to around 350,000 each
year. 鈥淭he figure for the healthcare costs is into billions and billions of
dollars a year,鈥� Oleszczuk says. 鈥淲e鈥檙e not even counting the psychosocial costs
for the families and for the triplets themselves, who have to deal with these
辫谤辞产濒别尘蝉.鈥�
Some countries have regulations that limit the number of embryos that can be
transferred in IVF, usually to just three. British authorities are considering
reducing that to two. But Brian Lieberman of Manchester Fertility Services, a
private clinic, thinks that doesn鈥檛 go far enough: 鈥淣one of these strategies
will suffice except for the replacement of a single embryo.鈥�
Advances in IVF technology could make this a viable option. Embryos are
usually transferred to the womb after 3 days, but new techniques allow them to
develop for 5 days into a ball of cells called a blastocyst. Transferring a
viable blastocyst gives much higher success rates
(快猫短视频, 17 October 1998, p 22).
Isaac Blickstein of the Kaplan Medical Center in Rehovot, Israel, says we
should ditch ovulation-inducing drugs altogether. 鈥淢aybe in the near future they
will be unethical,鈥� he says. He recommends that doctors switch over to IVF
instead.
If these policies were put in place, Oleszczuk says, rates of triplet births
could stabilise at natural levels within a few years.