Association of endogenous steroid levels with high and low density lipoprotein concentrations in the human maternal-fetoplacental unit at term.

OBJECTIVE

To determine the concentrations of high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), estradiol (E2), dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) in both maternal and venous cord blood upon delivery at term; to determine the degree of association between lipoprotein cholesterol concentrations and concentrations of selected steroid hormones, thus indicating correlations between regulatory mechanisms mediating steroid biosynthesis and cholesterol homeostasis in the maternal-fetoplacental unit; and to determine the efficacy of both heparin-manganese precipitation and agarose-gel electrophoresis techniques for quantitation of HDL-C and LDL-C in fetal and maternal plasma.

STUDY DESIGNS

Steroids were quantitated by radioimmunoassay in maternal and umbilical cord venous blood collected from 56 patients upon delivery. Correlation analysis and ANOVA were utilized to determine the degree of association between quantitative parameters in the total study population and differences in regard to fetal sex, respectively.

RESULTS

Values determined for all parameters measured fell within previously established normal ranges. HDL-C concentrations in the cord blood of female newborns were higher than those of males, while LDL-C concentrations were unchanged in regard to fetal sex. Concentrations of both LDL-C and all steroids measured in the maternal periphery were unchanged in regard to fetal sex, but HDL-C concentrations were higher in plasma of women bearing female fetuses. Further, LDL-C levels in cord blood positively correlated with maternal DHEAS levels and negatively correlated with maternal E2 levels. Cord E2 concentrations correlated highly with cord levels of both DHEA and DHEAS, and maternal E2 levels correlated, although to a lesser degree, with maternal DHEA concentrations.

CONCLUSION

The results indicated both positive and negative correlations of lipoprotein cholesterol levels with concentrations of the various steroid hormones associated with human pregnancy and illustrate the complicated interplay of mechanisms regulating steroid/lipoprotein metabolism in the maternal-fetoplacental unit. Changes in lipoprotein levels in the maternal-fetoplacental unit may suggest changes in steroid metabolism associated with fetal sex. Both heparin-manganese precipitation and agarose-gel electrophoresis techniques proved adequate for the quantitation of plasma lipoprotein cholesterol in both maternal and fetal plasma.