Q: I have really enjoyed reading your column on JPost.com, and have a question for you. How many ultrasounds are safe for a baby? Has there been any real research on the effects in this area? I’ve heard Israel does many ultrasounds comparatively, and would like to gather more information before going along with all the doctor says. Thank you so much for your help! SS
A: : Thank you for asking this important question. Ultrasounds are ultra-high frequency sound waves emitted by a transducer that is moved over the mother’s abdomen, producing a picture of the baby in the uterus. In Israel this diagnostic test is done routinely 2 – 4 times during the pregnancy, though some doctors (almost always those who have ultrasound equipment in their offices) perform ultrasounds at every prenatal visit.
Most ultrasound machines use pulses of ultrasound that last a fraction of a second. The time between the pulses is used to interpret the scan that returns to the machine. Doppler techniques used in specialized scans and fetal monitors use continuous waves of ultrasound.
The World Health Organization maintains that routine ultrasound testing has not been sufficiently evaluated to let the practice go unquestioned. The primary concern is the effect of ultrasound waves on fetal brains. The Federal Drug Administration (FDA) of the USA states, “Ultrasound is a form of energy and, even at low levels, laboratory studies have shown it can produce physical effects in the tissue, such as jarring vibrations and a rise in temperature.” They maintain that prenatal ultrasounds can’t be considered completely innocuous.
It is important to differentiate between selective and routine use of ultrasound. The time taken to do the scan, the type of equipment used and the experience of the technician also need to be examined. Ultrasounds can provide important information in specific clinical situations, such as if a fetus is alive or dead, to predict whether a pregnancy will continue after a threatened miscarriage and gestational age (particularly when this is done in the first or early second trimesters). Ultrasounds can also often diagnose a malformation and can be used with additional testing such as amniocentesis or chorion villus sampling and are used to assist procedures such as a cervical cerclage or external cephalic version (turning a breech baby). It can assess fetal growth in the second half of the pregnancy and can locate the position and health (grade) of the placenta. It can be used to confirm a suspected multiple pregnancy, assess the amount of amniotic fluid (this can vary based on the time of day and the amount of fluid ingested) and determine the fetal position (this can be assessed manually by a skilled practitioner).
Ultrasound waves affect the tissues in two ways. Firstly, the sonar beam heats the highlighted area and, secondly, the small pockets of gas that exist in the tissue being scanned vibrate and then collapse (an effect known as cavitation). Many animal studies have indicated that the effects of ultrasound waves can be harmful to the central nervous system.
Human studies have shown that ultrasound testing during pregnancy shows possible adverse effects including “premature ovulation, miscarriage or pre-term labor, low birth weight, poorer condition at birth, perinatal death, dyslexia, delayed speech development and less right-handedness. Non right-handedness (left-handedness and ambidexterity) is a consistent finding in many studies and is, in other circumstances, seen as a marker of damage to the developing brain.” (“Gentle Birth, Gentle Mothering” by Dr. Sarah J. Buckley, One Moon Press, 2005).
Many physicians claim that the benefits of ultrasound outweigh the risks, but a large randomized trial of 15,151 pregnant women, conducted by the RADIUS Study Group, found that in low-risk pregnancies, high-risk subgroups and even in cases of multiple gestations or major anomalies, the use of ultrasound did not result in improved outcome in the pregnancies (Ewigman, B.G. et al 1993 “Effect of Prenatal Ultrasound Screening on Perinatal Outcome” N. Engl. J. Med. 329 (12); 821-27). Some suggestion has even been made connecting frequent use of ultrasound in pregnancy with the steep increase in autism (“Questions about Prenatal Ultrasound and the Alarming Increase in Autism” by Caroline Rodgers in Midwifery Today, Winter 2006, # 80).
An important consideration in the decision to have ultrasound testing in pregnancy is the mother’s emotional attitude. Some women are eager to “see” their babies in utero and are more relaxed knowing that the baby is developing normally. This is often a positive step in developing the bond between the mother and her baby. Other women, however, feel that ultrasound is an invasion of the baby’s privacy and feel that the magical nature of the pregnancy is being medicalized.
Another consideration is what you plan to do with the information provided by the ultrasound. When used for diagnostic purposes, ultrasounds can lead to life-saving fetal surgery or can prepare specialists to be on hand at the birth to provide immediate care for a specific problem. However, when used routinely, ultrasounds can often be a cause for unnecessary anxiety without any benefit. Ultrasounds often pick up inconclusive abnormalities in late pregnancies when nothing can be done about them and the mother remains anxious until and frequently even after the birth which can adversely affect her bond with her baby.