It is known that memory begins during the prenatal period but little has been discovered about the exact timing or for how long memory lasts. A new study done in Holland has found fetal short-term memory in babies at 30 weeks in the womb.

The study provides insights into fetal development and may help address and prevent abnormalities, say researchers at Maastricht University Medical Centre and the University Medical Centre St. Radboud who published their results in Child Development.

The scientists studied about 100 healthy pregnant Dutch women and their fetuses, measuring changes in how the fetus responds to repeated stimulation. After receiving a number of stimuli, the fetus no longer responds to the stimulus as observed by ultrasonography and the stimulus is then accepted as "safe."

This change in response is called "habituation." In a second session, the fetus "remembers" the stimulus and the number of stimuli needed for the fetus to habituate is then much smaller.

Based on their research, the scientists found the presence of fetal short-term memory of 10 minutes at 30 weeks. They determined this because a significantly lower number of stimuli was needed to reach habituation in a second session, which was performed 10 minutes after the first session. They also found that 34-week-old fetuses can store information and retrieve it four weeks later. Fetuses were tested at 30, 32, 34, and 36 weeks, and again at 38 weeks.

The 34- and 36-week-old fetuses habituated much faster than the 38-week-old fetuses that had not been tested before. This implies that these fetuses have a memory of at least 4 weeks—the interval between the test at 34 weeks and that at 38 weeks.

"A better understanding of the normal development of the fetal central nervous system will lead to more insight into abnormalities, allowing prevention or extra care in the first years of life and, as a consequence, fewer problems in later life," according to the study's authors.

Reference: Child Development, Vol. 80, Issue 4, Aspects of Fetal Learning and Memory by Dirix, CEH, and Nijhuis, JG (Maastricht University Medical Centre), Jongsma, HW (University Medical Centre St. Radboud), and Hornstra, G (Maastricht University Medical Centre).