Fetuses Can Hear Ultrasound Examinations

New Scientist ^ | 12-04-2001 | Eugenie Samuel

[blam]

Fetuses can hear ultrasound examinations

10:04 04 December 01
Eugenie Samuel

Ultrasound examinations during pregnancy expose the fetus to a sound as loud as that made by a subway train coming into a station, say US researchers. But doctors do not think the experience causes a baby any lasting harm.

Neither adults nor fetuses can hear ultrasound waves because they vibrate at too high a frequency for our ears to detect them. But James Greenleaf, Paul Ogburn and Mostafa Fatemi of the Mayo Foundation in Rochester, Minnesota, investigated the possibility that ultrasound could cause secondary vibrations in a woman's uterus.

Ultrasound machines generate sound waves in pulses lasting less than one ten thousandth of a second. Pulses are used because a continuous soundwave could generate too much heat in the tissue being examined. The Mayo team predicted that the pulsing would translate into a "tapping" effect.

They listened in by placing a tiny hydrophone inside a woman's uterus while she was undergoing an ultrasound examination. Sure enough, they picked up a hum at around the frequency of the tapping generated when the ultrasound is switched on or off. The sound was similar to the highest notes on a piano.

Theoretical consequences

When the ultrasound probe pointed right at the hydrophone, it registered 100 decibels, as loud as a subway train coming into a station. "It's fairly loud if the probe is aimed right at the ear of the fetus," says Greenleaf.

Fredic Frigoletto, chief of maternal fetal medicine at Brigham and Women's Hospital in Boston, says doctors should be careful not to point the ultrasound probe directly at a fetus's ear unless there is a particular reason to suspect facial or cranial abnormalities. "Then the benefits significantly outweigh any theoretical consequences," he says.

Fatemi presented the team's research at the annual meeting of the Acoustical Society of America in Fort Lauderdale, Florida.

10:04 04 December 01

[Rodney King]

It's just a blob of cells, move along folks.

[slimer]

Imagine what they hear just prior to an abortion.

[llama7]

Actually, a woman I know refused to have ultrasounds done when she was pregnant. This was because she theorized that the rise in the use of ultrasound mirrored the rise in the number of children who experienced inner ear infections during childhood. So far, her daughter has not had an inner ear infection and is perfectly healthy.

Ultrasounds, for the most part, are a waste of time and money. I understand the utility of them, but only in circumstances where the procedure is actually beneficial to the health of the child (i.e. abnormalities appear in blood work, etc.).

Just because a person can not hear a sound does not mean that the sound does not have an effect on them. It's still energy.

[anniegetyourgun]

Horrors....

[Mind-numbed Robot]

Change the pulsing to Mozart and make them all smarter.

[ctdonath2]

I've long wondered about this. With such small, developing ears I expect the fetus could hear the ultrasound and be bothered by it. A good study would look for a correlation between such ultrasound use and later hearing ability.

100 decibels may be tolerable by children and adults, but I gotta wonder about "under-construction" fetuses.

[Dimensio]

It's just a blob of cells, move along folks.

If it's a fetus then it isn't a blob of cells anymore. I'm not aware of ultrasounds being used prior to the fetal stage -- I doubt you would be able to see anything anyway.

[Rodney King]

Ultrasounds, for the most part, are a waste of time and money. I understand the utility of them, but only in circumstances where the procedure is actually beneficial to the health of the child (i.e. abnormalities appear in blood work, etc.).

I am in my twenties, and have found that many of my friends have become pro-life after their ultrasounds showed human beings who resembled thier father or mother - and not the blob of cells that NOW wants them to think is in there.

If ultrasounds are not harmful, I think we should start a charity that pays for free ultrasounds at 3-4 months for every pregnant woman.

[Khepera]

Even the "Blob of cells" contain the same chromosome structure as the eventual adult human. So they are exactly the same only at different stages in life. Both are human, one would just be older.

[Rebelbase]

Impossible, everyone knows life begins after birth.

[homeschool mama]

**Actually, a woman I know refused to have ultrasounds done when she was pregnant. This was because she theorized that the rise in the use of ultrasound mirrored the rise in the number of children who experienced inner ear infections during childhood. So far, her daughter has not had an inner ear infection and is perfectly healthy. **

My daughter is almost 12 and has never had an ear infection. I should add...that I had 7 ultra sounds during pregnancy along with 5 stress tests...and an emergency birth. So, the theory *is* a theory.

[MarkWar]

>...a sound as loud as that made by a subway train coming into a station...

If that's _all_ it was -- and it only happened once -- what the heck. Subway noises? Train noises? The kids might as well get used to it.

Mark W.

[michaelje]

"Fetuses Can Hear Ultrasound Examinations"

No they dont, that just silly. The Boston Globe and NY Times told me its just a collection of cells. This is preposterous !

[babylonian]

Call me crazy, but I think a child in the womb is succeptible to friction, contention and arguments between their parents BEFORE BIRTH! Also, I think mothers who play music to their unborms have quite an affect on their babies. There's more to life than what we might think.

[Marie Antoinette]

Thanks, I was looking for more info on sonogram. With my last child the US caused more worry than it was worth. I was required to have 2 because of what the first one showed. There was NOTHING wrong with either the baby or me. Good birth, too!

[Britton J Wingfield]

It's still far less intrusive than the old "Poke'em with a stick" method.