Medical experts are issuing new warnings about frequent fetal ultrasound scans, noting American women have been getting them at sharply higher levels than ever before — sometimes merely to have images of their unborn children.

A joint statement from several medical societies, including the American College of Obstetricians and Gynecologists, says frequent scans in low-risk pregnancies aren’t medically justified and calls for just one or two in low-risk, complication-free pregnancies, the Wall Street Journal reports.

“Ultrasonogram should be used only when clinically indicated, for the shortest amount of time,” the statement said, referring to ultrasound scans, “and with the lowest level of acoustic energy compatible with an accurate diagnosis.”

In 2014, use of ultrasound scans averaged 5.2 per delivery — up 92 percent from 2004, according to an analysis of data compiled for the Journal.

Fetal ultrasound has never been shown to cause harm, but most research supporting its safety was conducted using equipment made before 1992, when it produced about one-eighth the energy it emits today.

The U.S. Food and Drug Administration warned last December against scans performed as keepsakes by some commercial businesses.

“Ultrasound can heat tissues slightly, and in some cases, it can also produce very small bubbles (cavitation) in some tissues,” the FDA noted, adding that “the long-term effects of tissue heating and cavitation are not known.”