Side Bar Articles - December 3, 2005
Preemies: Numbers growing, but chances are too
Magic in the mouse house
Preemies: Numbers growing, but chances are too
- A total of 7,272 babies were born at
Mount Sinai last year, of which 1,006
(13.8 per cent) were born preterm. Of
those, 44 were born 15 to 19 weeks
early (4.4 per cent); 140 came 10 to
14 weeks early (13.9 per cent); 223
arrived five to nine weeks early (22.2
per cent); and 599 came one to four
weeks before they were expected
(59.5 per cent).
- Normally, a pregnancy lasts 37 to
41 weeks; an infant born before 37
weeks is considered premature. In
2000, Canada’s preterm birth rate
was 7.6 per 100 live births, compared
with 6.6 in 1991. The rate
ranged from 5.8 per cent in PEI to
10.4 per cent in Nunavut.
- In the United States, about one in
eight live births is premature — the
preterm rate has jumped 33 per cent
since 1981, when Washington began
tracking such births. Among black
women, almost one in five babies is
premature.
- In industrial countries, prematurity
accounts for 60 to 80 per cent of
deaths of infants without congenital
disorders.
- To a great extent, the causes of prematurity
remain a mystery. About half
the women who deliver early have no
known risk and most of those identified
as high-risk deliver on time.
- Although scientists can’t point to
any major cause for the increase in preterm babies, one that is frequently
cited is the increase in multiple
births from fertility drugs and in-vitro
fertilization. Also, more babies are
being born to older women, who are
more likely to have problems such as
high blood pressure and diabetes,
which can lead to premature births.
- A “very premature” baby is born before
32 weeks’ gestation. Statistics
show that 1.2 per cent of singletons,
11 per cent of twins and 31 per cent
of triplets fit in this category.
- Triplets are 12 times more likely to
die during the first year than singletons.
On average, triplets are born seven
weeks earlier and at half the
weight of the average singleton infant, and at least 25 per cent are very
underweight at birth — less than
1,500 grams.
- Until the 1990s, the very survival of
a baby of 28 weeks was considered a
miracle. The death rate was 80 per
cent. With advances in lung care, 80
per cent of these babies now survive.
- Neonatologists agree that every
day a baby stays inside a mother’s
body is a bonus. The earlier the delivery,
the higher the odds of disabilities
such as cerebral palsy, brain bleeding,
blindness and deafness. At 22
weeks’ gestation, the chances of
such severe problems are 75 per
cent, dropping to 40 per cent a week
later and to 5 per cent at 28 weeks.
- Even preemies who escape major
problems tend to be short, weigh
less, have recurrent infections and
are more likely to have trouble at
school. Hernias are commonly seen.
- The smallest baby ever to survive is
believed to be Rumaisa Rahman of
Chicago, who celebrated her first
birthday this September. At birth, Rumaisa
— the smaller of twins —
weighed 244 grams when she was
delivered at 25 weeks and six days by
cesarean section. She was no bigger
than a Barbie doll and weighed less
than a can of soda. She required six
months of hospital care and was still
on round-the-clock oxygen when she
went home.
Magic in the mouse house
- Next fall, a state-of-the-art home for genetically altered
mice will open in Mount Sinai Hospital. The $68-million
Toronto Centre for Phenogenomics (TCP), a partnership
of four University of Toronto teaching hospitals, will
be one of the world’s most comprehensive facilities for
studying the treatments of, and cures for, humanity’s
chronic diseases.
- Although they don’t look it, humans and mice are very
similar species, sharing 95 per cent of their 30,000
genes. Mice have the same embryonic development,
disease patterns and behavioural problems as humans.
And they get stressed too.
- Researchers first genetically engineered mice in
1980. These mutants, usually with one gene added,
subtracted or altered, are no longer a scientific curiosity.
They have been used for 15 years as models of human
diseases. Now, scientists worldwide aim to recreate
all the main human ailments — diabetes, heart disease,
cancer and mental illness — in the mouse.
(Because genes often work their influence throughout
an entire organism, mere cell cultures are not enough.)
Observers predict that, in future, the mouse will be pivotal
to medicine.
- Mount Sinai’s 120,000-square-foot TCP will house
36,000 cages — holding roughly 180,000 mice. Its researchers
will freeze embryos and sperm of mutant
mice and distribute them to academic and private-sector
research partners, through the Canadian Mouse
Consortium. They will also archive and distribute genetically
altered mice worldwide. The TCP is part of an international
effort to figure out the functions of all the
genes in a mouse.
- So far, “simple” genetic engineering has created such
mutants as fearless mice, “nude” mice without immune
systems, tireless “marathoners” and mice extremely
addicted to nicotine. However, because many
diseases such as diabetes and cancer are caused by
multiple gene malfunctions, mice with more complex
genetic strains will be needed.
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