Ultrasound and Adverse Effects in Pregnancy: Where Research Stands Today

Monitors showing prenatal ultrasound imaging

Prenatal ultrasounds are a standard part of pregnancy care, giving parents a window into fetal development and helping providers assess growth, anatomy, and well-being. But with any procedure that involves energy—especially during pregnancy—questions sometimes come up about safety.

Could ultrasounds cause harm to your baby?

According to scientific research and expert consensus, there is no conclusive evidence that routine diagnostic ultrasounds cause adverse effects during pregnancy. When used responsibly, ultrasound remains a safe and effective tool in obstetric care.

Below, we explain what the science says about ultrasound and adverse effects, including what researchers continue to study and why the technology is considered safe when guidelines are followed.

Understanding Ultrasound’s Biological Effects

Diagnostic ultrasound works by using high-frequency sound waves to create images of the fetus. It is considered a form of energy, and any energy that interacts with tissue has the theoretical potential to cause changes. Because of this, researchers have explored whether ultrasound might be linked to possible adverse effects.

The two most commonly discussed concerns are thermal effects and mechanical effects, such as cavitation.

Thermal effects

One area of interest in ultrasound safety is the potential for thermal effects—specifically, the slight increase in tissue temperature that can occur as ultrasound waves pass through the body. This warming is measured using the Thermal Index (TI), which helps estimate the potential for heat generation during a scan.

In obstetric imaging, the TI is kept within levels that are recognized as safe for fetal tissues, including those still in the early stages of development. Studies have not confirmed harmful outcomes when ultrasounds are performed within these low levels.

To further minimize any theoretical risk, healthcare professionals follow the ALARA principle—“As Low As Reasonably Achievable”—by limiting exposure time and adjusting equipment settings to use only as much energy as needed to obtain accurate diagnostic images.

Mechanical effects

In addition to thermal changes, researchers have also studied the potential mechanical effects of ultrasound, particularly a phenomenon known as cavitation. Cavitation refers to the formation of microscopic gas bubbles within tissues due to rapid pressure fluctuations caused by ultrasound waves.

Clinicians use the Mechanical Index (MI) to assess the likelihood of cavitation. The MI reflects the potential for ultrasound waves to produce mechanical changes in tissue. Obstetric ultrasounds are performed with an MI well below the safety threshold, significantly reducing the chance of any biological interaction.

Further reassurance comes from a 2023 study that evaluated the potential for cavitation in human tissue. Researchers found no evidence of cavitation nuclei—the structures required to initiate bubble formation—in gas-free tissues like those commonly scanned during pregnancy.

Potential for Other Adverse Effects

While thermal and mechanical effects are the most well-studied biological interactions of ultrasound, some researchers have explored whether ultrasound exposure might influence broader outcomes in child development.

A few observational studies have reported possible associations with outcomes such as low birth weight, delayed speech, dyslexia, and non–right-handedness. However, other studies have not demonstrated these effects, and the evidence remains inconsistent.

One large analysis published in Ultrasound in Obstetrics & Gynecology reviewed data from 41 studies, including controlled trials, cohort studies, and case-control analyses. The researchers examined a wide range of outcomes, from perinatal complications to childhood growth, neurological development, handedness, malignancy, and cognitive performance. Their review found no conclusive link between ultrasound exposure and adverse maternal or fetal outcomes, nor did they find evidence of long-term developmental harm.

There was a weak association between prenatal ultrasound exposure and non-right-handedness in boys, but the authors noted that this finding was of limited clinical significance and not indicative of a causal relationship.

The study concluded that diagnostic ultrasound, when used within recommended parameters, is not associated with harmful outcomes. These findings align with current medical consensus and the position of many leading institutions.

The Cleveland Clinic states that there are no harmful side effects to you or your baby when undergoing diagnostic ultrasound. Similarly, the U.S. Food and Drug Administration (FDA) reports that ultrasound has an excellent safety record when used appropriately by trained professionals.

The American College of Obstetricians and Gynecologists further supports this, noting that “...currently, there is no evidence that ultrasound is harmful to a developing fetus. No links have been found between ultrasound and birth defects, childhood cancer, or developmental problems later in life.”

Balancing Curiosity and Caution

It’s perfectly understandable to want more information when weighing the benefits and potential risks of any diagnostic tool during pregnancy. Research on ultrasound and adverse effects is ongoing, not because routine scans are unsafe, but because science continually aims to validate the safety of evolving technologies.

To date, there is no proven link between diagnostic ultrasound and cavitation, miscarriage, preterm labor, low birth weight, intrauterine growth restriction, or neurological outcomes. Claims about adverse effects of ultrasound—such as developmental issues or cognitive delays—have not been confirmed in well-controlled, peer-reviewed studies.

As long as ultrasound is used appropriately and performed by trained professionals, it is believed to be one of the safest imaging tools available during pregnancy.

Learn More About Safe Prenatal Imaging

At Nola Diagnostic Ultrasound, your comfort and confidence are always a priority. All scans are performed by a registered sonographer with over a decade of experience in ultrasound imaging and a strong background in maternal-fetal medicine.

Our lead sonographer is certified by the American Registry for Diagnostic Medical Sonography (ARDMS) and holds credentials in OB/GYN, abdominal, vascular, and pediatric ultrasound. This depth of expertise ensures that your prenatal scan is conducted with the highest standards of safety, precision, and care.

Whether you’re preparing for your first appointment or have questions about the possible adverse effects of ultrasound, we’re here to support you with clear information and compassionate service.