Quantitation of some urinary oligosaccharides during pregnancy and lactation

The excretion rates of different oligosaccharides in the urine of two individuals, a blood group O, nonsecretor woman, and a blood group A, secretor woman, were studied at different times during pregnancy and lactation. Quantitative determinations of di-, tri-, and tetrasaccharides were performed by combined gas-liquid chromatography-mass spectrometry. Larger oligosaccharides were quantitated by their content of total hexose or 6-deoxyhexose (fucose). The urinary oligosaccharide excretion during pregnancy is detectable by the 13th week. All oligosaccharides studied increased and reached the highest levels during the last trimester. During lactation more complex excretion patterns were observed. Lactose and oligosaccharides with a lactose backbone were the most predominant compounds. Oligosaccharides with a lacto-K-tetraose or a lacto-N-neotetraose backbone were present both during pregnancy and lactation, but the former type showed a much more pronounced increase of excretion during lactation. Four oligosaccharides containing only D-glucose were found in largest amounts during pregnancy. One of these oligosaccharides, a glucose tetrasaccharide, was quantitatively determined in the urine of 13 individuals and the excretion was found to decrease 2- to 5-fold in the first week post partum relative to the last week of pregnancy. Urine from a woman whose fetus died unexpectedly in the 24th week of pregnancy was also studied. No oligosaccharides characteristic of a normal pregnancy could be detected, suggesting that at least some oligosaccharides appearing specifically during pregnancy might reflect the function of the placenta or the fetus, or both.