Gut bacteria alter women's metabolism during pregnancy

Changes in the 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 supply the fetus with nutrients as fully as possible.

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

It is known that changes in the composition of intestinal microflora can provoke metabolic disorders, the development of metabolic syndrome, obesity and diabetes. Patients with metabolic syndrome have increased levels of glucose, fats and inflammatory markers. Researchers have noted that the same thing happens to pregnant women: molecular signs of inflammation appear, the content of glucose and fats in the blood increases. To answer the question of whether bacteria are the cause of these changes, scientists analyzed bacterial DNA taken from the stool of women at different stages of pregnancy.

In an article published in the journal Cell, the authors write that between the first and third trimesters, women experience a steady decline in the species diversity of their intestinal microflora, while the number of bacteria from the Proteobacteria and Actinobacteria groups increases significantly. Exactly the same changes occur in people with obesity and metabolic syndrome. The fact that such a shift occurs in pregnant women by the third trimester seems entirely justified. At this time, the child begins to rapidly gain weight, and the increased level of glucose and fats caused by the bacterial shift comes in very handy.

Changes in the intestinal microflora do not harm the mother's health, although, as has already been said, the content of inflammatory markers in the blood increases. Moreover, these changes occur regardless of the state in which the woman entered 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 the standard "pregnant" state. However, the composition of the newborn child's own microflora will be similar to the mother's, which the woman had in the first trimester, that is, before all these changes.

The researchers conducted experiments with rats that were freed from their own gastrointestinal bacteria and then given samples of microflora taken from women at different stages of pregnancy. Rats that received third-trimester microflora began to accumulate fat, and their tissues became less sensitive to insulin, i.e., they stopped absorbing glucose from the bloodstream. In other words, metabolic changes in the mother’s body apparently really do begin with changes in the bacterial microflora of the intestine. According to the authors of the work, microorganisms sense the physiological changes that accompany pregnancy and adapt to them so that the growing child’s body is supplied with nutrients as fully as possible. Which again speaks to the highest degree of symbiosis between a person and his intestinal bacteria.

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