Baby crying decoded by science

The prolonged crying of babies worries parents, disrupts family life and gives rise to numerous medical consultations. Today, the latest scientific studies allow us to better understand them in order to better respond to them.

The intestinal track

A baby cries, everyone knows it. But sometimes it is excessive and those around the newborn are completely at a loss. If the disproportionate nature or not of this crying depends on the tolerance threshold of the parents, medicine nevertheless gives a very precise definition. We talk about excessive crying when it lasts more than three hours a day and more than three days a week. Late-night crying is particularly characteristic: some babies cry every day for two to three hours between 18 p.m. and midnight, and nothing manages to soothe them. ” Crying is a means of expression and communication, the only one the infant has, but it is a language difficult to decipher “, Recognizes Dr Pierre Foucaud straight away. Research therefore got down to it. Why do some babies cry more than others? Several studies carried out in Scandinavia have measured in the blood of the umbilical cord, a hormone playing a role in the motor skills of the digestive tract, motilin. Babies born with high motilin have been shown to suffer more from colic and therefore from prolonged crying. “In these studies, we can clearly see that the intensity of crying and screaming is proportional to the level of motilin. This hormone is particularly produced in large quantities when the baby is subjected to smoking by his mother in utero. Or when it is exposed to it at birth. And these smoky babies have been shown to suffer more from infant colic. This suggests that there would be an intestinal hormonal cause for excessive crying, ”explains Dr Bellaïche. To be credited with these studies: their publication in recognized scientific journals.

Baby crying: no miracle cure

But the story does not end there. Italian researcher continued to explore the intestinal trail and found a particularly low level of lactobacilli in the stools of newborns suffering from colic. He had the idea of ​​giving these infants these “good” bacteria for the digestive tract: a strain isolated in Sweden, swallowed by these babies at the rate of 5 drops per day for three weeks. At the end of this study, this researcher measured the time of crying. “The result is exceptional: 95% of newborns who took these drops cried significantly less than those who did not. The methodology of this randomized, double-blind study was perfect. And it was reproduced three years later, ”enthuses Dr. Bellaïche. Moreover, the Swedes, convinced by these studies, marketed the famous drops containing the precious bacteria, also sold in France. “But this is not a miracle product, tempers Dr Bellaïche. When I prescribe them to my little patients, only a third is noticeably improved. “” This research must be confirmed by other teams to be credible. And for the moment, this is not the case, ”estimates Dr. Foucaud for his part. In any case, how should we react to a crying baby? Should we console him immediately or let him cry? A question that all parents ask themselves. At one time, babies were allowed to cry under the pretext that they had to “do their lungs” and that they should not be made capricious children. But today science tells us more.

Before 4 months, the baby must be comforted quickly

A study carried out in New Zealand and published this summer in the journal Early Human Development has indeed revived this debate. The researchers followed infants aged 4 to 10 months for five days. Objective: to teach them to fall asleep without help. In an adjoining room, their mothers could hear their crying but were not allowed to intervene. Every day, researchers measured the levels of cortisol, the stress hormone, in the saliva of babies and their mothers. On the first day, infants cried for an average of twenty minutes. An increase in cortisol levels has been seen in children and mothers. From the third day, the babies stopped crying, but their cortisol levels were still high. The mothers, a priori reassured by the stop of the cries, saw them, their level of cortisol collapsing. Suddenly, many deduced that these babies remained stressed but gave up showing it. A conclusion that would prove the supporters of “let it cry” wrong. For Dr Foucaud, “This interpretation is too simplistic! Reducing the increase in salivary cortisol just by stress seems illusory. This hormone has multiple functions. In addition, the study concerns babies from 4 to 10 months and not infants of a few weeks who present the famous “colic”. Making a biological marker an educational indicator borders on the scientific imposture. ”

On the other hand, other more serious studies go in the same direction and show for example thata quickly consoled baby would cry less by the age of one year, without becoming a tyrant. “It is important to quickly console a baby under 4 months old and to decode his language,” confirms Dr Foucaud. At this age, crying means an unmet need : hunger, discomfort, sleep, need for skin to skin, presence… We must not forget that the infant has had a close relationship with his mother in utero. He cannot acquire his autonomy in a few weeks, ”he assures us. “For older babies, parents can allow themselves ten minutes before hugging them, while reassuring them orally. But all the situations are different, we cannot generalize, ”he concludes.

Rule out a medical cause

The famous American pediatrician Thomas Brazelton found that a baby cries the most at the age of 6 weeks. At the time, he called these incessant crying colic. Hence the expression “infant colic”. However, studies show that, when we explore the colon of these crying babies, they do not suffer a priori from organic lesions of the digestive tract but from a hormonal or bacterial imbalance. On the other hand, it is necessary to consult so as not to miss out on a real health problem: the most common are an allergy to cow’s milk proteins, constipation, lactose intolerance or gastroesophageal reflux.

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