Table 1.

Ontogeny models investigated

Model	Equation1
Linear2	(a * AGE) + b
Power2	b *AGEa
Exponential2	b * ea * AGE
Linear-Log2	b + [a *ln(AGE)]
Sigmoid Emax3	$\frac{{\mathit{AAG}}_{\mathit{max}}\ast {\mathit{AGE}}^P}{T{M_{50}}^P+{\mathit{AGE}}^P}$

¹the covariate AGE was specified using either postnatal age (days) or postmenstrual age (weeks)

²a and b denote estimable parameters associated with the linear, power, exponential, and linear-log models

³AAG_max (maximum plasma AAG concentration [mg/dL]), TM₅₀(age at 50% AAG_max [days or weeks]), and P (Hill coefficient) denote estimable parameters associated with the sigmoid Emax model