Factors affecting the lipid and apolipoprotein levels of cord sera.

In studying the human lipid transport system as it changes from the fetal to the adult form, data were collected on cord sera levels of lipids and apolipoproteins (A-I, A-II, ApoB, C-I, C-II, C-III, ApoD, and ApoE) from infants whose lipid metabolism might have been modified by a variety of factors present before, at, or after delivery. The results clearly indicated that many factors affect the levels of both lipids and apolipoproteins at birth. Method of delivery had little effect except in relation to either fetal immaturity (increased total cholesterol) or fetal stress (increased triglycerides). Birth weight was related to changes in free cholesterol, C-I, C-III, and ApoE levels. Gestational age had greater impact upon both serum lipids and apolipoproteins. With increasing fetal maturity, total cholesterol, free cholesterol, A-II, C-II, and ApoE progressively fell whereas triglyceride and ApoD rose. A variety of clinical disorders were also associated with changes in serum lipid and apolipoproteins. Anencephaly produced marked increases in both free and total cholesterol as well as most apolipoproteins. Significant reductions in triglyceride and ApoD levels were found in infants who subsequently became ill in the postnatal period with problems relating to carbohydrate metabolism (e.g., infants of diabetic mothers). Infants with respiratory distress were found to have decreased levels of total cholesterol and ApoB, both of which are increased in prematurity, a condition with which respiratory distress (RD) is usually associated. The changes in cord sera lipid and apolipoprotein levels found in a variety of clinical situations may provide new diagnostic approaches to postnatal problems arising in the newborn.