iwszonek
30.04.04, 04:56
Oto, co wyczytałam na temat bezpieczeństwa usg. Nie chcę niekogo straszyć,
sama miałam już robione to badanie kilka razy i dopiero teraz mnie oświeciło,
że może lepiej było się powstrzymać.
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Ultrasound scans may disrupt fetal brain development
17:56 10 December 01
Ultrasound examinations may disrupt normal brain development in unborn
babies, say Swedish scientists. They have urged mothers-to-be to avoid
unnecessary ultrasonic scans, but not cancel routine examinations.
"Ultrasound is misused at times," says Helle Kieler of the Karolinska
Institute in Stockholm, Sweden. "There are a lot of ultrasound examinations
performed which are not needed."
Some mothers even seek videos of ultrasonic scans just to keep as mementoes,
says Francis Duck, chairman of the European Committee for Medical Ultrasound
Safety at the Royal United Hospital in Bath, UK.
Kieler's team studied a group of Swedish men born between 1973 and 1978.
Nearly 7000 had received ultrasonic scans in the womb, while 170,000 had not.
Kieler found that of the men born between 1976 and 1978 who had ultrasonic
scans in the womb, 32 per cent more than expected were left-handed. In an
average population, around nine per cent of men are left-handed.
The scientists took account of factors such as premature birth, birth weight
and maternal age, but admit that they cannot rule out post-natal
environmental influences for the effect they found.
The results suggest that some men who genetically would have been expected to
be born right-handed had actually grown up to be left-handed. Kieler says
this could be due to a disruption of their brain development in the
womb: "It's commonly known among neuropsychiatrists that right-handed people
can become left-handed by slight damage to the brain."
Wider window
She says it is significant that the effect was only found in men born in 1976
and later. That year, it became common in Sweden for expectant mothers to
have two ultrasonic scans - one after 17 weeks of pregnancy and another after
37 weeks.
Currently in the UK, women typically have one or two ultrasonic scans during
pregnancy, although more can be recommended to track a particular condition
in the fetus.
In a study published in 1999, Kieler found that handedness of girls was not
affected by ultrasound. The difference, she says, could be down to the way
the brain develops in each sex.
"Brain development in males takes place over a longer period compared with
the female, so there's a wider window for external factors to have an
effect," she says.
Vibrating bubbles
How ultrasound could affect the brain is still a mystery though. Kieler
suspects that a process called cavitation - where small bubbles in the body
fluids vibrate in the ultrasonic waves - could influence brain development.
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Weblinks
Medical epidemiology, Karolinska Institute
British Medical Ultrasound Society
European Federation of Societies for Ultrasound in Medicine and Biology
Epidemiology
"In the early stage of pregnancy, neurons migrate from the centre of the
brain and this could be disturbed by ultrasound, maybe by cavitation," she
says.
"This is a big gap in our knowledge," says Duck. "If ultrasound is having
this effect, we have to take it seriously, but right now, we just don't know
what is going on."
Duck adds that ultrasonic scans are needed to track fetal development and to
check for abnormalities. "It would be inappropriate for people to start
cancelling their appointments, but this ought to act as a real stimulus for
more work on this," he says.
Journal reference: Epidemiology (vol 12, p 618)
