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Dr. Gail Gross Headshot

Effect of Stress on the Language Learning Ability in the Womb

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Did you know that babies learn in the womb, and also that stress can affect their development?

A study by Patricia Kuhl, Ph.D., Bezos Family Foundation endowed chair in early childhood learning and a professor of speech and hearing sciences at the University of Washington in Seattle, stated that babies not only hear their mother's voice and understand their mother's inflection, but they are also already learning her language in the womb. This is the foundation for language. In fact, just hours after birth, a baby can distinguish between a mother's native tongue and the foreign language of another mother.

Because a mother's voice is magnified and amplified by her body, it can be heard by her baby, along with other sounds in utero. Babies also are already making sense of the sounds they hear. By hearing speech patterns and rhythms in the womb, babies are learning their primary language. Hence, some researchers believe that a mother can facilitate her child's language development, both in the womb and after birth.

Teaching sound recognition

Studies now indicate that we can even teach babies before birth. We now know that the fetus is so sensitive stimulation from the mother affects them directly. Studies using EEG sensors, which search for neural traces of memory in utero, indicate that sound repetition becomes a part of memory. Therefore, if the sound is replicated, that memory is activated. When a fetus is introduced to a repeated sound, their memory of that sound stimulates its' recognition. As a result, brainwave patterns of the fetus indicate the memory of the recognized sound.

In a study by cognitive neuroscientist Eino Partanen and others, of the University of Helsinki, infants' brains not only learned repeated sounds, but also recognized words and their variations. Partanen's study demonstrated that the neural signals for identifying sound, including vowels, are visible as memory traces in a new-born.

Ten weeks before birth, fetuses use many of their senses to learn about their inner world. Ultrasounds show us that a fetus will react to noise by kicking, moving and even dancing around, in the womb, and bobbing up-and-down when mother laughs. Further, a fetus's heart-rate, may lower upon hearing mother's voice. They may touch their face, suck their thumb, stretch their limbs hold their feet and have enough coordination to grasp their own umbilical cord with their fingers. Fetuses have even been viewed through ultra-sound as licking the uterine wall and pushing off of it with their feet. Most prenatal sleep occurs in REM. Fetus sleep for most of the day and night while dreaming -- probably about their own environment. And twin fetuses, after 20 weeks, play with each other and even demonstrate fear and anger.

Christie Moon, Ph.D., a psychologist at Pacific Lutheran University in Tacoma, Washington, along with Dr. Hugo Lagercrantz, a professor at the Karalinska Institute in Sweden and a member of the Nobel Assembly, co-authored a study, with Dr. Patricia Kuhl, which used a pacifier on newborns, to measure, by computer, the frequency of sucking, experienced by newborns, when they heard his/her native language. Each suck related to a produced vowel. The infant paused when unfamiliar vowels were introduced, and each new suck produced the next vowel sound. Two sets of vowels sounds were used. Seventeen foreign language sounds were used in conjunction with seventeen native language sounds.

This study indicates that babies remember elementary sounds from their mother as early as ten weeks before birth. Further, the neurosensory mechanism for hearing is intact at 30 weeks of gestational age. Therefore, phonetic learning occurs in the womb. And, past studies indicate that the fetus both responds and remembers musical rhythm. Now we know they are laying the foundation for language development and are, in fact, partially learning a language. This study and others like it, indicate that the brain is very sophisticated in utero and is capable of listening and learning language.

Stress During Pregnancy

According to Professor Vivette Glover of Imperial College London, stress during pregnancy can increase the risk for early cognitive problems. For example, cortisol stress hormones can cross the placenta. Therefore, high levels of cortisol in ambiotic fluid affects the dopamine production in the brain. It appears that consistent stress to the mother can cause an overly sensitized baby who has a lower stress threshold after birth.

Moreover, a mother's stress can affect her baby permanently. For example, a receptor for stress hormones can cause a biological change in the fetus, which makes it more vulnerable to stress after birth -- this links to hyperactive disorders. Also, a correlation to stress in the womb, can lead to later auto-immune problems.