Ultrasound
Ultrasound is a form of energy produced from high frequency waves, or pulses of sound lasting less than one ten-thousandth
of a second. These pulses of sound, the equivalent of acoustical radiation, are beyond the range of human hearing. These
ultrasonic waves are beamed into the body and bounce back from different surfaces and densities in different organs. The interval
between the waves are used to interpret the echo that returns. These “echoes” are converted into electrical impulses, which
are processed to form sound and pictures for use in medical examination of a baby in utero. Obstetric ultrasound can cause a
heating effect on tissue, up to 2°F, and the bubbling motion of cells (known as cavitation) can produce toxic gasses that have an
unknown effect on the growing baby.
Can my baby hear it?
Ultrasound during pregnancy can expose a fetus to a sound as loud
as that made by a subway train coming into a station, up to 100-120 decibels, however because ultrasound is outside the range of human
hearing the baby cannot hear it the way we can hear an actual subway train. However one research study indicated that the pulse
of the ultrasound could be detected as a tapping sound when the ultrasound machine was turned on and off. This tapping was similar
to the highest notes on piano, and the fetus may respond by moving the head back and forth in response to the sound and vibration
in the bones of the inner ear. This activity in the baby can produce an increase in heart rate and the baby may move more during
the scan, or attempt to move away from the probe.
What does the medical community have to say about the use of ultrasound?
The American College of Obstetrics and Gynecology (ACOG), Federal Drug Administration (FDA), American Medical Association and the
American Institute for Ultrasound in Medicine all recommend against routine ultrasound, and have deemed the non-medical use of ultrasound
for psychosocial or entertainment purposes to view the fetus, obtain a picture, or determine gender without a medical indication as
inappropriate and contrary to responsible medical practice.
What are the risks of ultrasound?
Measuring the risk 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 which, if affected, could have serious long-term
implications. Because a baby grows rapidly, exposing it to ultrasound at 8 weeks can have different effects than exposure at,
for example, 10, 18 or 24 weeks. The rapid development of each new variation of ultrasound has not been accompanied by similar
careful evaluation by controlled, large-scale trials. Thus the full risks of ultrasound in humans is not well studied and difficult
to prove equivocally in humans. There have been literally thousands of studies done on the safety of ultrasound, and while there
is no definitive evidence of risk, there is some good evidence that it can cause permanent cellular changes in the brain of a developing
fetus as supported by an increase in left-handedness, and there is good research to indicate it can cause intrauterine growth restriction.
What is a doppler?
A doppler is a hand-held device used to detect the heartbeat of the fetus. An ultrasound machine
used to view a sonogram and a doppler both use ultrasound, however a doppler uses a continuous beam of ultrasound instead of an intermittent
wave. One minute of doppler use is the equivalent of 35 minutes of a visual sonogram.
Northeast Kansas Homebirth
Service uses a stethoscope or fetoscope to detect heart tones, which sometimes takes patience. A doppler is rarely used prenatally unless
heart tones cannot be heard with a stethoscope or fetoscope due to baby’s position, noise, gestational age, etc., but always with
consent only. A sonogram is not recommended unless there is a clear medical indication that birth at home may be inadvisable
in the presence of certain complications, and an ultrasound may potentially give a definitive diagnosis. You should consider
your options thoroughly regarding ultrasound use, and examine your motives carefully if you feel the need to obtain a sonogram for
any other reason, or for routine use of the doppler.
References
“Fetal Effects of Ultrasound: A Growing Controversy,” by
Doris Haire, Journal of Nurse-Midwifery, 29:4, p241
“Sonograms Aren’t Safe…Dopplers Are Worse” by Tracy West-Lauer, AAMI
“Ultrasound
in Controversy,” by Jay Hathaway
Guide to Effective Care in Pregnancy, 1st ed., p48-56
Mothering #102, p58-61
Midwifery Today #50, p30;
#51, p31-33; #64, p28
Understanding Lab Work in the Childbearing Year, 4th ed., p402-406
www.birthlove.com/pages/sarah/ultrasound.html
www.fda.gov/fdac/features/2004/104_images.html
www.fetalsure.com/fetal-doppler-safety.html
www.plus-size-pregnancy.org/Prenatal%20Testing/prenataltest-ultrasoundsafety.htm
www.unhinderedliving.com/pultra.html
