Background and Aims
The aims of this study were to investigate lipid parameters during the first 14–16 months of life, to identify influential factors, and to test whether high concentrations at birth predict high concentrations at 2- and 14–16 months.

Methods
The Copenhagen Baby Heart Study, including 13,354 umbilical cord blood samples and parallel venous blood samples from children and parents at birth (n = 444), 2 months (n = 364), and 14–16 months (n = 168), was used.

Results
Concentrations of lipids, lipoproteins, and apolipoproteins in umbilical cord blood samples correlated highly with venous blood samples from newborns. Concentrations of low-density lipoprotein (LDL) cholesterol, non-high-density lipoprotein (HDL) cholesterol, apolipoprotein B, and lipoprotein(a) increased stepwise from birth to 2 months to 14–16 months. Linear mixed models showed that concentrations of LDL cholesterol, non-HDL cholesterol, and lipoprotein(a) above the 80th percentile at birth were associated with significantly higher concentrations at 2 and 14–16 months. Finally, lipid concentrations differed according to sex, gestational age, birth weight, breastfeeding, and parental lipid concentrations.

Conclusions
Lipid parameters changed during the first 14–16 months of life, and sex, gestational age, birth weight, breastfeeding, and high parental concentrations influenced concentrations. Children with high concentrations of atherogenic lipid traits at birth had higher concentrations at 2 and 14–16 months. These findings increase our knowledge of how lipid traits develop over the first 14–16 months of life and may help in deciding the optimal child age for universal familial hypercholesterolaemia screening.