Health services are this week starting an expanded, safer
screening programme to detect Down's syndrome during
pregnancy, after serious flaws were detected in the old
system.
All women who see a midwife or doctor in early pregnancy will
now be offered a blood test in addition to the existing
ultrasound scan.
The blood test is free, but the scan usually costs about $30
to $40.
Those who present later will, as now, be offered a blood
test, but a new kind.
Those considered at higher risk of carrying a fetus with
Down's syndrome, other chromosomal disorders or spina bifida,
because of the screening tests results and maternal age and
weight, are offered diagnostic testing.
Analysis commissioned by the Health Ministry since 2004 found
the screening system was ad hoc and that women were putting
their babies' lives at unnecessary risk.
It is expected the new programme will reduce referrals for
amniocentesis, an invasive test that has a 0.5% to 1% chance
of causing a miscarriage.
This is the main diagnostic test for Down's syndrome and is
done on 5% of all pregnant women.
It involves inserting a needle into the uterus and taking a
sample of the fluid surrounding the fetus for laboratory
testing.
The analysis found the test was being done on some women who
might not have an increased chance of having a child with
Down's syndrome and who had not had the miscarriage risk
explained to them.
Peter Stone, the professor of maternal fetal medicine at
Auckland University and the author of a report on the
screening system, concluded in 2006 that "more normal
pregnancies may be adversely affected by amniocentesis than
the numbers of Down's syndrome fetuses detected".
Down's syndrome is caused by the presence of an extra
chromosome.
It results in intellectual disability and an increased risk
of some physical problems, including heart disease.
It is linked to increasing maternal age and the risk rises
steeply after 35.
New Zealand's incidence of Down's syndrome rose from 0.87 per
1000 lives births in 1996 to 1.48 (80 Down's syndrome babies)
in 2002.
Jane McEntee, the manager of ante natal and newborn screening
at the ministry's National Screening Unit, said last night
New Zealand had been screening for Down's syndrome for 30
years, but the system had fallen behind international
practices.
"This is about making sure the screening is safe and reliable
and that women are fully informed around what screening means
and what may follow screening and any decisions that they may
need to make.
"So with the screening they can be informed and make
decisions around what support is available if there was going
to be a child with a disability or the decisions they make
that are appropriate for them."
The ministry has said its review of the screening is not
about reducing the number of babies born with Down's
syndrome.
