Gut bacteria alter women's metabolism during pregnancy

Changes in intestinal microflora in pregnant women are similar to those that occur in patients with obesity and metabolic syndrome, but in the case of pregnancy, such changes in the composition of microorganisms help to provide the fetus with nutrients as fully as possible.

Intestinal microflora in a pregnant woman changes so that the fetus does not lack nutrients. This conclusion was reached by researchers from Cornell University (USA), having analyzed the species composition of gastrointestinal bacteria in women at different stages of pregnancy. Although now there is a real boom of work devoted to the relationship between the intestinal microflora and the host organism, no one has yet tested how the gastrointestinal bacteria behave in women who are about to give birth.

It is known that changes in the composition of the intestinal microflora can provoke metabolic disorders, the development of metabolic syndrome, obesity and diabetes. In patients with metabolic syndrome, the level of glucose, fats and inflammatory markers is increased. Researchers drew attention to the fact that the same happens with pregnant women: there are molecular signs of inflammation, the content of glucose and fats in the blood increases. To answer the question of whether bacteria cause these changes, scientists have analyzed bacterial DNA taken from women's stools at different stages of pregnancy.

In an article published in the journal Cell, the authors write that between the first and third trimester, a stable drop in the species diversity of the intestinal microflora is observed in women, while the number of bacteria in the Proteobacteria and Actinobacteria groups is greatly increased. Precisely the same changes occur in people with obesity and metabolic syndrome. The fact that in pregnant women this shift occurs to the third trimester, it looks quite justified. At this time, the child begins to gain weight, and the increased level of glucose and fats, provoked by a bacterial shift, is very useful.

Changes in the intestinal microflora do not harm the health of the mother, although, as already mentioned, the content of inflammatory markers in the blood increases. Moreover, these changes occur regardless of the state of the woman who entered into pregnancy. Whether she was overweight or not, whether there was a risk of developing diabetes, whether she took antibiotics or probiotics - the intestinal microflora will still strive for a standard "pregnant" condition. However, the newborn's own microflora in composition will be similar to the mother's that was in the woman in the first trimester, that is, before all these changes.

Researchers conducted experiments with rats that were relieved of their own gastrointestinal bacteria, and then gave them samples of microflora taken from women at different stages of pregnancy. Rats that received the microflora of the third trimester, began to accumulate fat, and their tissues became less sensitive to insulin, that is, they ceased to absorb glucose from the bloodstream. In other words, the metabolic changes in the mother's body seem to start with the reconstruction of the bacterial intestinal microflora. According to the authors of the work, microorganisms feel the physiological changes accompanying pregnancy, and adjust to them so that the growing body of the child as fully as possible is supplied with nutrients. That again speaks about the highest degree of symbiosis between a person and his intestinal bacteria.

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