Ultrasound uses high-frequency sound waves to create images of structures inside the body. During pregnancy, it visualizes the developing fetus and monitors maternal health. While ultrasounds are a routine part of prenatal care, concerns about their frequency are common. This article provides information on ultrasound safety during pregnancy.
Why Ultrasounds Are Performed
Ultrasounds serve various purposes throughout pregnancy, providing information about the developing baby and maternal health. Early in pregnancy, an ultrasound can confirm the pregnancy, determine gestational age, and check for multiple pregnancies. They also ensure the pregnancy is located within the uterus and detect an embryonic heartbeat.
As pregnancy progresses, ultrasounds monitor fetal growth and movement, assess the baby’s heart rate, and check the amount of amniotic fluid. A detailed anatomy scan, typically around 18 to 20 weeks, examines fetal structures like the spine, limbs, brain, and internal organs. Ultrasounds also assess placental position and identify potential complications or anomalies.
Current Understanding of Ultrasound Safety
Diagnostic ultrasound is safe for the fetus when performed by trained professionals for medical reasons. Unlike X-rays, ultrasound uses sound waves and does not involve ionizing radiation. This distinction is important, as ionizing radiation carries known risks.
Decades of research and widespread clinical use establish a safety record for diagnostic ultrasound. Major health organizations, such as the American Institute of Ultrasound in Medicine (AIUM) and the American College of Obstetricians and Gynecologists (ACOG), state ultrasound is safe when used appropriately. These organizations advocate for the “As Low As Reasonably Achievable” (ALARA) principle, using the lowest possible ultrasonic exposure and scanning time to obtain necessary diagnostic information.
Examining Concerns About Frequency
Concerns about ultrasound frequency relate to theoretical bioeffects: thermal and mechanical (cavitation). Thermal effects involve a temperature rise in tissues due to sound energy absorption. Mechanical effects, like cavitation, refer to the oscillation or collapse of microscopic gas bubbles within tissues.
While these bioeffects can occur at very high intensities or prolonged exposure, diagnostic ultrasounds use low power and brief exposure times. There is no conclusive scientific evidence linking routine, medically indicated ultrasound examinations to adverse fetal outcomes. Current diagnostic ultrasound levels are below thresholds that would cause significant harm.
It is important to distinguish between medically indicated diagnostic ultrasounds and non-medical “keepsake” ultrasounds, performed solely for entertainment or images. Professional medical bodies discourage keepsake ultrasounds because they may not adhere to medical safety protocols or the ALARA principle. The U.S. Food and Drug Administration (FDA) discourages unapproved use of medical devices without a physician’s order.
Medical Recommendations for Ultrasound Use
The number of ultrasounds a pregnant person receives is determined by medical necessity, not a routine schedule. Healthcare providers follow established guidelines for appropriate and effective use. For low-risk pregnancies, one or two routine scans are typical, with a significant scan around 18-20 weeks to assess fetal anatomy.
Additional scans might be indicated in high-risk pregnancies or when complications arise. Reasons for more frequent ultrasounds include monitoring fetal growth, evaluating vaginal bleeding, assessing the placenta, or guiding procedures like amniocentesis. These guidelines prioritize the health and safety of the pregnant individual and the baby, ensuring ultrasounds are performed only when a clear medical benefit exists.