When does the baby begin to listen?

Studies on foetal psychism have reinforced that newborns have sound

The idea that the uterus functions for the fetus as a closed box throughout gestation, and that babies are born, as Locke said, “tabula rasa”, fell apart a few decades ago. Today we know that the child is in interaction with the external environment since the intrauterine life and that, when he comes into the world, he already has a certain baggage of experiences.

As pregnancy progresses, many women speak to the babies growing in their wombs. Some mothers-to-be sing lullabies or read stories. Others play classical music in an effort to boost brain development. Many encourage their partners to communicate with the baby too.

Studies on foetal psychism have reinforced that newborns have sound, visual and olfactory preferences. In addition, they seem to memorise their mother’s voice and recognise melodies. Today, you will discover why it is important to stimulate the foetus from the last trimester of pregnancy, when the baby begins to hear and how this can influence its personality and development.

The foetus perceives the external world

We consider the foetal stage to be the period from the beginning of the ninth week of gestation until the birth of the baby. By the third month the fetus takes on an obviously human form, its cerebral hemispheres grow and other important parts of the central nervous system are formed, such as the cerebellum and the first connections between neurons (synapses).

At the end of this period he is already able to make several movements, such as kicking, opening and closing his hands and mouth, and swallowing. Around the 20th week, or 5th month, the baby begins to hear. However, he is only able to process low-frequency sounds, and this function improves as gestation progresses.

In the sixth month, the eyes are formed and able to look in all directions. The nervous system is also much more mature from the 24th week. It is here that myelination occurs, that is, the neurons gain a fatty sheath along their axons, which gives agility to the conduction of stimuli.

The seventh month marks the final stage of pregnancy. Here the foetus is already able to differentiate between light stimuli that determine day and night, and can see the outline of its own body and the umbilical cord. It is estimated that during this phase the development of self-consciousness and awareness of the outside world takes place and the foetus begins to show more interest in its mother’s voice.

During the entire gestation period the foetus is maturing in an environment that is also influenced by the mother’s blood pressure changes, hormone release and other stimuli, such as trauma or caresses. Thus, no baby is subject to identical conditions between them, given the particularities of the environment to which each pregnant woman is vulnerable.

The foetus has emotional life

Contrary to what many people think, the fetus does have an emotional life before coming into the world. In fact, it is extremely sensitive and some traces of its personality may already be evident even in the way it moves inside the belly. According to some studies, the affective condition of the fetus is directly related to the emotional state of the mother and how she disposes herself in relation to the child. The foetus is capable of feeling pleasure, pain, sadness, joy, fear, well-being, anguish and of capturing the mother’s emotional states.

This happens because, when experiencing the most diverse types of feelings, the nervous system of the pregnant woman releases neurotransmitters into her bloodstream, and these substances are able to cross the placental barrier. But, calm down, you don’t need to worry too much. These stimuli are only really harmful when they are very frequent. A woman, for example, who is constantly under stress or who has a depression condition prior to pregnancy may manifest chemical and inflammatory mediators that are transmitted to the baby.

According to a study published in the Journal Psychoneuroendocrinology, these chemical stimuli can cause foetal suffering, limitation of growth or influence the behaviour of the newborn, its affective relationship with the mother and its cognitive organisation capacity. If this is your case, be sure to talk to your obstetrician and keep your mental health monitoring up to date, right?

Babies learn through sound while still in the womb

The ultrasound imaging technique allowed us to learn a little bit about the interaction of babies in utero with the outside world, but this was not the only technology to help us in this task. The advent of the hydrophone, a small microphone capable of capturing sound in an aqueous medium, revealed to us a sound environment never before imagined inside the womb.

We then discovered that the baby’s playlist is composed of the sound of the mother’s heartbeat, blood flow, peristaltic movements and breathing. More than that: he is also able to hear sounds from the outside world, including the mother’s and other people’s voices, ambient noises, the mother’s gait, and, amazing music! Sound transmission can occur through touch, via bone conduction, and through hearing, via the air. It is clear that external sound is not perceived by the fetus in the same way that it is perceived by us, since it needs to cross various physical barriers in its path.

Will my baby-to-be recognize my voice?

As your baby grows, more sounds will become audible to them. Around week 25 or 26, babies in the womb have been shown to respond to voices and noise. Recordings taken in the uterus reveal that noises from outside of the womb are muted by about half.

Studies on foetal psychism have reinforced that newborns have sound, visual and olfactory preferences. In addition, they seem to memorise their mother's voice and recognise melodies. Today, you will discover why it is important to stimulate the foetus from the last trimester of pregnancy, when the baby begins to hear and how this can influence its personality and development.

That’s because there’s no open air in the uterus. Your baby is surrounded by amniotic fluid and wrapped in the layers of your body. That means all noises from outside your body will be muffled.

The most significant sound your baby hears in the womb is your voice. In the third trimester, your baby can already recognize it. They will respond with an increased heart rate that suggests they are more alert when you’re speaking.

What sound does the baby recognise?

It is estimated that these barriers acoustically impair noise and distort the sound of consonants, for example. Vowels, the tone of speech and musical melodies, on the other hand, seem to be well recognised from the 6th month, although some researchers believe that this does not occur until around the 32nd week.

The fact is that, as of the 6th month of life, you can and should talk to your baby, play music for him to hear, and stimulate him by touching and caressing his belly. When you touch or massage the belly, the vibrations caused by the liquid inside the uterus also give the foetus a tactile experience. Don’t forget: Dad should take part in these moments. This way, when the baby begins to hear his parents’ voices, it becomes easier to create a bond and recognise similarities in the postnatal period.

Babies are able to retain memories of life in the womb

An experiment by Decasper & Spencer (1986) hypothesized that, yes, our babies do retain memories of life inside the womb. The researchers asked some pregnant women, at seven and a half months gestation, to record with their own voice three short children’s stories. Only one of these stories was to be read to the baby on every day of the last 6 weeks of pregnancy.

In the postpartum period, these women had a device attached to their breasts that allowed them to activate the recording of the stories according to the rhythm of the child’s sucking at the breast. If the suction was fast, the story chosen by the mother during pregnancy was activated; if it was slow, one of the stories not chosen was played. The result? Well, as it turned out, the little ones sucked faster to hear the stories they were familiar with, suggesting some kind of memory of life in the womb.

Is it or isn’t it the most beautiful thing the way mother and baby establish a progressive bond during pregnancy? With the giant contribution of science, we eventually discovered you can invest in the relationship with your baby even before he arrives, as well as providing extra substrate for his future interest in the outside world.

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