Learning in the Womb

Dive Deeper
Newborns can recognize songs, stories, words and smells that they were exposed to 6 weeks before they were born. (Image Credit: Science Source)
What can a fetus remember?

Although no one remembers their experience in the womb, the fetus can form memories that last for weeks.1 For example, newborns remember sounds and tastes that they experienced in the womb. Two and three-day-old infants preferred hearing a story that their mother had read out loud twice a day during the last 6 weeks before birth.2 Newborns this age also prefer a familiar lullaby that their mothers sung while they were pregnant compared to a new lullaby.3 Newborns also showed a preference for classical or jazz music when their mother had listened to one of these selections of music twice a day during the last 6 weeks before birth.4 Interestingly, this preference can be observed when the music was played at 34 weeks after conception, but not at 28 weeks after conception, suggesting that learning familiar sounds occurs after 28 weeks.5

Habituation

Historically, researchers studied habituation to determine whether the fetus could learn. Habituation is a decrease in response to a stimulus after multiple presentations. For example, in 1925, a German researcher honked a car horn repeatedly and observed that the fetus jumped less and less with more and more repetitions.6 The earliest habituation responses have been demonstrated at 20-21 weeks after conception and seem to occur earlier in females than in males.7  In another real-world example of fetal habituation, researchers studied mothers who moved to the Osaka airport neighborhood before the last four months of their pregnancy and found that their babies did not wake up or show significant changes in brain activity as measured by an electroencephalogram (EEG ) when the researcher played a recorded aircraft noise at 80dB. In contrast, these babies woke up when they heard an unfamiliar music sequence at the same volume – 80dB.8 Also, babies with more prenatal exposure to airplane noise slept better than babies whose mothers had only lived in the area near the airport for a short time.9

Recognition

Learning can also be documented from one prenatal age to another. Interestingly, non-startling sounds evoke mild heart-rate decelerations in the womb, whether the fetus appears to be awake or asleep in the womb.10 In a clever study that uses this change in fetal heart rate, researchers asked mothers to read a nursery rhyme out loud starting at 26 weeks after conception and 30 weeks after conception. They found that fetuses who started at 26 weeks after conception took 5 weeks to learn the rhyme, as shown by a heart-rate deceleration, but fetuses who started at 30 weeks after conception learned the rhyme in just two weeks.11 In a follow-up study, researchers asked women to recite a rhyme from 26 to 32 weeks post-conception. They assessed the fetus’s learning by recording heart rate decelerations and found that the fetus had usually become familiar with the rhyme by 32 weeks after conception and that he remembered the rhyme at 36 weeks post-conception, even though he had not heard the rhyme in four weeks.12

How long can this learning last?

In a more recent study, mothers listened to a descending piano melody twice a day during her 33rd through 35th week after conception. Then six weeks later, after their babies were born, the melody was played again while the babies quietly slept. All babies respond to music by slowing down their heart rate, but the babies who had heard the music before had a heart-rate deceleration that was twice as large as the babies who had never heard the music before.13 This was the first example of learning in utero that lasted many weeks after birth. Another group asked pregnant women to listen to a melody five times per week from 27 weeks after conception until birth. When they studied brain activity in these infants, they found that both at birth, and at four months old, these infants responded to the familiar melody with greater brain activity than babies who had never been exposed to the melody.14 The more that the babies had heard the melody prenatally, the stronger their brain response.15 Other researchers have had difficulty seeing this long-lasting prenatal learning, perhaps because they used fewer prenatal exposures.16

How does transnatal learning help the newborn?

New evidence suggests that newborns can learn speech sounds from their native language in utero. One group of researchers gave pregnant women a recording including made-up words like “tatata” and “tatota” interspersed with music to play five to seven times per week from 27 weeks after conception until birth. By the time that the babies were born, they had heard the made-up words more than 25,000 times. Amazingly, when these babies were tested after birth, their brains showed the neural signals for recognizing vowel changes in the middle of the made-up word. The signal was strongest for babies whose mothers had played the recording most often.17 These results provide convincing evidence that language learning begins in the womb.

(Image Credit: Science Source)
Can the fetus remember tastes and smells?
...if a mother eats garlic while she is pregnant, her newborn exhibits less aversion to garlic than newborns whose mothers did not eat garlic.18

Finally, the fetus also learns about tastes and smells. For example, if a mother eats garlic while she is pregnant, her newborn exhibits less aversion to garlic than newborns whose mothers did not eat garlic.19 Similar results have been seen for anise and vanilla.20 Furthermore, when women frequently drank carrot juice during their third trimester, their babies showed less aversion to carrot-flavored cereal when they started eating solid foods six months later.21 This suggests that taste-learning lasts for months and may be more robust than auditory learning in the fetus.

Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion
Sperm-egg fusion