The Role of Microbiota in Newborn Babies

The role of microbiota in newborn babies is very important in the development of their immune system. It begins to form in the uterus and has a decisive advance after birth, thanks to breastfeeding to a large extent.
The Role of Microbiota in Newborn Babies

Last update: 16 June, 2021

Microbiota in newborn babies is a topic that’s been gaining importance in recent times, as research found it plays a fundamental role in the maturation of a child’s immune system and in the regulation of their intestinal mucosa.

In turn, an adequate immune system is fundamental for the normal development of a child. We now know that the microbiota of the newborn baby plays a decisive physiological role in their organic balance. Likewise, there’s a decisive relationship between the microbiota and the so-called atopic diseases.

We also now know that the way a child comes into the world determines the composition of their newborn’s microbiota. That is, it changes depending on whether the birth is natural or by C-section. Feeding with breast milk or formula also has a decisive influence on this.

The microbiota

Various types of gut microbiota.

Microbiota comprises all the microorganisms in the intestine, the urogenital tract, and the nasal and oral cavities. Estimates indicate there are about 38 million bacteria in the intestine alone and at least 1,000 different species.

People used to refer to the microbiota as intestinal flora or microbiological flora. Its composition varies and its specialty is the area of the organism it inhabits. These microorganisms interact with the body and carry out some of its functions.

The composition and distribution of the microbiota are also closely related to diet. The link between it and some atopic and inflammatory diseases is currently under thorough study.

The microbiota in newborn babies

This is already present to some extent during the fetal stage but begins to develop at birth. The baby acquires a microbiota similar to that of their mother’s vagina when the birth is natural. Microorganisms reach it through the mother’s skin and even from the doctors in those born by C-section.

In addition, newborn babies’ immature immune system begins to develop thanks to the microbiota. These microorganisms provide the stimulus their organism requires to activate the immune system.

In turn, receptors in the cells of the immune system that recognize the bacteria, viruses, and fungi that comprise the microbiota capture these stimuli. Thus, it triggers a series of biochemical signals that lead to immune tolerance. For example, the absence of an immune reaction against these microorganisms. In addition, inflammation occurs when something goes wrong.

Intrauterine programming and colonization

A baby in the womb.

We used to think the fetus didn’t have any microorganisms in its body while in utero. However, recent research just reevaluated this idea. Thus, we now know the microbiota begins to form from the placenta and amniotic fluid.

At birth, there’s a process of maternal-fetal microbiological transfer. Then, the intestinal colonization of the newborn begins. This is a dynamic process influenced by several factors such as the type of delivery and the food the child receives, among others.

At the beginning of life, after birth, there’s also a process of competition between the microorganisms that’ll form part of the microbiota and pathogens. The abundance of nutrients is decisive for the establishment of the intestinal microbiota. The microbiota is able to deter pathogens if it consolidates.

Breastfeeding and newborn microbiota

Breast milk also plays a decisive role in the establishment of the newborn’s microbiota. It provides the new organism with immunological factors, as well as prebiotics and probiotics, among others. All of these together regulate the colonization of microorganisms in the baby’s body.

An interesting fact is that researchers have established that the baby’s intestinal maturation improves by introducing probiotic supplements in the mother’s diet. They’ve also established that diets rich in vegetable fiber have the same effect.

Likewise, studies revealed that the children of mothers who consume fermented foods and give breast milk to their babies are less predisposed to suffer from certain atopic diseases, such as asthma and food intolerances.

Finally, reports indicate that alterations in the establishment of the microbiota increase the risk of diseases such as obesity, diabetes, and various types of allergies.

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  • Barboza, L. (2013). Tolerancia inmunitaria. Avances en Biomedicina, (1), 40-42.
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