Do you jump when your cell phone rings unexpectedly? New research shows that sound may also startle an unborn baby.

Researchers asked 28 pregnant resident physicians who constantly carry cell phones and/or beepers at work to undergo fetal testing known as a biophysical profile while the devices were activated. The women were all between 27 and 41 weeks gestation.

During each screening session, the gadgets were set off at intervals of 5 minutes five times. Fetal responses including head turning, mouth opening and were recorded from several angles. All of the fetuses demonstrated an initial startle response. Additional stimulations were associated with varying decreases in response. The researchers say, “Repeated startle responses may be worrisome because they interfere with the known normal cycle of fetal behavior.”

They are calling for more research into potential adverse pregnancy outcomes related to cell phones and beepers.