It has been hypothesized that plasma triglyceride fatty acids may traverse the placenta and contribute to infant adiposity particularly in GDM pregnancy. It has also been hypothesized that high-density lipoproteins (HDL) can both deliver cholesterol to and remove cholesterol from the placenta. To determine if these maternal parameters are related to fetal growth in normal pregnancy, we have examined relationships of lipoprotein lipids, apoproteins, hormones, fuels, clinical chemistries, and maternal weight at 36 wk gestation to infant birth weight, birth weight ratio (birth weight corrected for gestational age), birth length, and head circumference in a cohort of pregnant women attending a prepaid health plan, Group Health Cooperative of Puget Sound. Associations were examined using a multivariate regression analysis of several groups of related variables. Results show that the birth weight and/or birth weight ratio are weakly positively associated with maternal very-low-density lipoprotein (VLDL) triglyceride and statistically significantly positively associated with apoprotein A-I, placental lactogen, estradiol, bilirubin, and maternal prepregnancy weight and pregnancy weight gain. Glucose and insulin predict birth weight only in pairwise analysis. Significant negative predictors of birth weight or birth weight ratio include VLDL cholesterol, apoprotein A-II, SGOT, and creatinine. Significant positive predictors of birth length include apoproteins A-I, placental lactogen, and maternal weight. Apoprotein A-II negatively predicts birth length. Only maternal prepregnancy weight predicts head circumference. The results are compatible with the hypothesis that triglyceride fatty acids cross the placenta and contribute to fetal adiposity in normal pregnancy and that the process can be exaggerated in the hypertriglyceridemic GDM woman. The positive association of apoprotein A-I and the strong negative association of apoprotein A-II with birth weight and length point to a physiologically significant role for HDL subfractions in fetal growth, possibly relating to the provision of cholesterol for placental steroid hormone synthesis and fetal cellular proliferation.