The progressive increase in the intensity of metabolism, both in the mother's body and in the fetus, causes an increased strain on the urinary organs. The main changes that arise in the operation of the glomerular-tubular kidney system mentioned here. In addition, it should be noted that in addition to changes in the filtration and reabsorption of water and electrolytes, the intensity of these processes for glucose also changes (for pregnancy, glucosuria is characteristic even at its normal level in the blood), the final products of protein metabolism (increased excretion of urea, creatinine) uric acid. At the end of pregnancy, a certain amount of protein can be removed (not more than 0.1 g /l).
During pregnancy, especially in the second half, the ligamentous apparatus of the kidneys weakens, which leads to their pathological mobility. The cup-lohan system is expanding. Often, these factors lead to a stasis of urine and venous stasis, which, combined with the suppression of the tone of the ureters, against the background of increased action of progesterone, creates the conditions for the development of pyelonephritis.