To determine whether small for gestational age (SGA) infants show changes in lipid metabolism that could distinguish growth-restricted subpopulations.Methods
Sera from the arterial cord blood from 38 SGA infants were analyzed for apolipoprotein A-I level, total lipid content, and distribution of those lipids as triglycerides, diglycerides, free fatty acids, and phospholipids. Comparisons were made between appropriate for gestational age (AGA) controls (n = 25), SGA infants with a ponderal index below the tenth percentile (SGA I, n = 20), and SGA infants with a ponderal index above the tenth percentile (SGA II, n =18).Results
Total cord serum lipid content was markedly decreased in all SGA infants compared with AGA infants (2.8 times lower). Although SGA infants showed total lipid concentration decreases, SGA I and SGA II infants showed distinct characteristics. Infants in the SGA I group had higher triglyceride levels (1.8 times higher) and lower free fatty acid levels (1.4 times lower), compared with AGA infants (P < .001). The lipid subclass distribution in SGA II infants was not significantly different from that in AGA infants, with the exception of an increase in triglyceride concentrations (1.3 times higher). Although the 22-kD placenta-derived apolipoprotein A-I was similar in all groups, the level of fetal liver–derived 28-kD apolipoprotein A-I was 6.5 times lower in SGA I infants than in AGA or SGA II infants (P < .001).Conclusion
The SGA I infants appeared to have impaired utilization of circulating triglycerides, consistent with peripheral adipose depletion. Diminished fetus-derived apolipoprotein A-I levels with normal levels of placenta-derived apolipoprotein A-I levels might indicate a defect in the production or secretion of apolipoproteins associated with growth restriction.