SERUM LIPIDS AND LIPOPROTEINS IN FULLTERM NEWBORNS DURING THE FIRST FEW DAYS OF LIFE

Summary It was shown that the total lipids, total and free cholesterol as well as the phospholipids of serum from umbilical cord blood are much lower than in normal adults. The investigation of lipoproteins in serum from umbilical cord blood showed that the α‐lipoproteins represented about 43 per cent and the β‐lipoproteins about 33 per cent. This ratio is likewise different from that found in normal adults, where the corresponding figures are about 30 per cent and 50 per cent. During the first 12 hours of life the total lipids, total cholesterol and phospholipids increase by about 10–15 per cent. This increase does not vary with the time between birth and collection of the sample. It is suggested that this increase might be due to a dehydration of the blood during the first postnatal hours, during which no changes occur in the lipoprotein distribution. During the first few days all the serum lipids increased steadily. Supplementary diet during the first day of life did not appear to accelerate the increase in serum lipids. During the first few days of life the increase of the serum lipids was accompanied by a marked change in the ratio between the α‐ and β‐lipoproteins. Thus on the fourth day the α‐lipoproteins represented 29 per cent and the β‐lipoproteins 46 per cent of the total lipids, a ratio corresponding roughly to that found in normal adults. Quantitatively, however, all the lipoproteins showed an absolute increase during that time. The most marked increase was that of the β‐lipoproteins which was more than 100 per cent. It was shown that the ratio of the combined to free cholesterol, which in the adults varied within narrow limits (2.3–3.1), is much lower (1.3–2.3) in umbilical cord blood. During the first few days of life both the combined and the free cholesterol increase in absolute amount, but with no change of the ratio between them. The cholesterol‐phospholipid quotient, which is about 0.90 in adults is about 0.60 in umbilical cord blood and increases to about 0.65 during the first few days of life. None of the data studied appeared to vary with sex or body weight at birth. The values found for children delivered by Caesarian section were not found to differ from the values found for children delivered by the normal route.