Fetuses can form memories, an important indicator of nervous-system maturation that may help doctors detect developmental problems, Dutch researchers say. Fetuses exposed to sound and vibration for 1 second every 30 seconds became accustomed to the stimuli, a process known as habituation. "Habituation is a form of learning," a study co-author tells the Los Angeles Times.
Younger fetuses retained memories for 10 minutes, and the older they got, the longer their memories extended. Habituation takes longer in fetuses with developmental problems, such as Down syndrome, than in those that are growing normally. "The fetus needs to know which sounds are stressful and which are safe," said the researcher. "Otherwise, it would be completely distressed all day long because it hears noises of the maternal gut and heart."