Fetal Ultrasounds: Are They Truly Safe?

Fetal ultrasounds - which were introduced in the 1960s - have long been regarded as a safe means of checking on the health of your unborn baby. But some are now saying...they may not be as safe as previously thought.

Ultrasound Information: How Does An Obstetric Ultrasound Work?

An ultrasound scanner uses high-frequency sound waves to give x-ray-like images of the inside of the womb, but without using radiation, which carries a risk of causing cancer.

Between the 1960s and today, the number of pregnant women having scans in western Europe and in the United States has increased from a handful to virtually all of them.

In the United States the rate in 2006 was over 70%.

This rate is probably on the low end now that many OBGYNs have ultrasound equipment in their offices and they perform one at nearly every visit.

Ultrasound uses sonar technology to produce the image of your baby on the screen. Sound waves bounce off your baby's body to produce the images.

The same technology is used in Doppler devices - a device used during prenatal appointments to listen to your baby's heartbeat.

The frequency of the sound waves varies from between 3 and 8 MHz. The lower the frequency, the deeper the sound wave can penetrate.

An obstetric ultrasound is believed by most doctors to be completely safe. However, some women - as well as some scientists - have begun to question the safety of routine fetal ultrasounds in pregnancy.

Are Fetal Ultrasounds Dangerous To My Baby?

Ms. Karen Pollard, lecturer with the School of Clinical Sciences at CSU said:

Concern?

Yes, and for good reasons.

Read on.

Ultrasound Information: Ultrasound Safety

During the 1990s, a number of studies hinted that fetal ultrasounds affected unborn babies. In fact, in 1993, Dr. Newnham and his colleagues sounded the alarm about the safety of ultrasounds.

In a randomized controlled trial involving 1,400 Australian women, they found that women who had ultrasound five times during pregnancy gave birth to babies with lower birth weight than women who had an ultrasound only once.

Low birth weight reflects less than optimal brain growth.

In the most comprehensive study to date - published in Epidemiology December 2001 12:618 - on the effects of ultrasound technology on unborn babies, scientists may have found evidence suggesting that the scans do cause brain damage.

Researchers have found that men born to mothers who underwent scanning were more likely to show signs of subtle brain damage. Research has suggested that subtle brain damage can cause people who ought genetically to be right-handed to become left-handed. In addition, these people face a higher risk of conditions ranging from learning difficulties to epilepsy.

A team of Swedish scientists has confirmed the earlier reports on the effects of ultrasound with the most compelling evidence so far. Their conclusion is that indeed unborn babies are affected by the obstetric ultrasound.

They compared almost 7,000 men whose mothers underwent scanning in the 1970s with 170,000 men whose mothers did not, looking for differences in the rates of left and right-handedness.

The team found that men whose mothers had scans were significantly more likely to be left-handed than normal, pointing to a higher rate of brain damage while still in the womb.

The biggest difference was found among men born after 1975, when doctors introduced a second fetal ultrasound later in pregnancy. Such men were 32 per cent - 1/3! - more likely to be left-handed than those in the control group. The researchers warned that fetal ultrasounds in late pregnancy were now routine in many countries.

Normally, left-handedness is genetic: the likelihood of two left-handed parents having a left-handed child is 35 per cent, while for two right-handed parents, it is only nine per cent. It is when the incidence of left-handedness begins to rise above these normal rates that scientists become concerned that brain damage of some kind could be a factor.

Other surveys have shown that premature babies are five times more likely than normal to be left-handed.

According to the Swedish researchers, the human brain undergoes critical development until relatively late in pregnancy, making it vulnerable to damage. In addition, the male brain is especially at risk, as it continues to develop later than the female brain.

The growing evidence that fetal ultrasounds affect unborn babies may cast new light on the puzzling rise in left-handedness over recent years. In Britain, the rate has more than doubled, from five per cent in the 1920s to 11 per cent today.

Beverley Beech, the chairman of the Association for Improvements in Maternity Services, criticized doctors for insisting for years that ultrasound was totally safe:

If this was not enough evidence, in August 2006, we were given the results of another study...

...which is even more disturbing as it links fetal ultrasounds to autism.

Read on.

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