Prenatal Ultrasound
It is ironic that women who have had previous miscarriages often have additional ultrasound examinations in order to "reassure" them that their baby is developing properly. Few are told of the risks of miscarriage or premature labour or birth.
Obstetricians in Michigan studied fifty-seven women who were at risk of giving birth prematurely. Half were given a weekly ultrasound examination; the rest had pelvic examinations. Preterm labour was more than doubled in the ultrasound group?52%?compared with 25% in the controls.(1) Although the numbers were small, the difference was unlikely to have emerged by chance.
A large randomized controlled trial from Helsinki randomly divided more than 9,000 women into a group who were scanned at 16 to 20 weeks compared with those who were not. It revealed 20 miscarriages after 16 to 20 weeks in the screened group and none in the controls.(2)
A later study in London randomized 2475 women to routine Doppler ultrasound examination of the umbilical and uterine arteries at 19 to 22 weeks and 32 weeks compared with women who received standard care without Doppler ultrasound. There were 16 perinatal deaths of normally formed infants in the Doppler group compared with 4 in the standard care group.
It is not only pregnant patients who are at risk, however. Physiotherapists use ultrasound to treat a number of conditions. A study done in Helsinki found that if the physiotherapist was pregnant, handling ultrasound equipment for at least 20 hours a week significantly increased the risk of spontaneous abortion.(3)
The Saari-Kemppainen study also revealed the lack of value in early diagnosis of placenta praevia. Of the 4000 women who were scanned at 16 to 20 weeks, 250 were diagnosed as having placenta praevia. When it came to delivery, there were only four. Interestingly, in the unscanned group there were also four women found at delivery to have this condition. All the women were given caesarean sections and there was no difference in outcomes between the babies. Indeed, there are no studies that demonstrate that early detection of placenta praevia improves the outcome for either the mother or the baby. The researchers did not investigate the possible effects on the 246 women who presumably spent their pregnancies worrying about having to undergo a caesarean section and the possibility of a sudden haemorrhage.
There has been inadequate research into the potential long-term effects. Measuring the outcome of any intervention in pregnancy is very complicated because there are so many things to look at. Intelligence, personality, growth, sight, hearing, susceptibility to infection, allergies and subsequent fertility are but a few issues that, if affected, could have serious long-term implications, quite apart from the numbers of babies who have a false positive or false negative diagnosis. Because a baby grows rapidly, exposing it to ultrasound at eight weeks can have different effects than exposure at, for example, 10, 18, or 24 weeks. This is one of the reasons the effects of potential exposure are so difficult to study. Women are now exposed to so many different types of ultrasound: Doppler scans, real-time imaging, triple scans, external fetal heart-rate monitors, hand-held fetal monitors. Unlike drugs, whereby every new drug must be tested, the rapid development of each new variation of ultrasound machine has not been accompanied by similar careful evaluation by controlled, large-scale trials.
Despite decades of ultrasonic investigation, no one can demonstrate whether ultrasound exposure has an adverse effect at a particular gestation, whether the effects are cumulative or whether it is related to the output of a particular machine or the length of the examination. How many exposures are too many? What is the mechanism by which growth is affected? ? It should not be forgotten that numerous studies on rats, mice and monkeys over the years have found reduced fetal weight in babies that had ultrasound in the womb compared with controls. Nor should it be forgotten that in the monkey studies the ultrasound babies sat or lay around the bottom of the cage, whereas the little control monkeys were up to the usual monkey tricks. Long-term follow up of the monkeys has not been reported. Do they reproduce as successfully as the controls? And, as Jean Robinson has noted, "Monkeys do not learn to read, write, multiply, sing opera, or play the violin." Human children do, and perhaps we should consider seriously whether the huge increases in children with dyslexia and learning difficulties are a direct result of ultrasound exposure in the womb. Furthermore, when a woman is scanned her baby's ovaries are also scanned. So if the woman had seven scans during her pregnancy, when her pregnant daughter eventually presents years later at the antenatal clinic, her developing baby will already have had seven scans. Do women really know what they consent to when they rush to hospital to have their first ultrasound scan, then trustingly agree to further scans?
? Beverley Lawrence Beech
excerpted from "Ultrasound: Weighing the Propaganda Against the Facts,"
Midwifery Today Issue 51
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