Table 4.

Mixed-effects regression model predicting the association between total NISS and salivary cortisol concentrations (log nmol/L).

Variables		β	95% CI	P-value
Total NISS		0.03	0.002, 0.05	0.04*
Female Sex		0.01	−0.21, 0.24	0.90
Postmenstrual Age		−0.09	−0.14, −0.04	<0.001*
Birth weight z-score		−0.01	−0.14, 0.12	0.83
Gestational Age		0.06	−0.02, 0.15	0.16
Race/ ethnicity
	Non-Hispanic White	Ref.	Ref.	Ref.
	Non-Hispanic Black	0.14	−0.16, 0.43	0.36
	Hispanic	0.04	−0.33, 0.41	0.83
	Others	0.05	−0.22, 0.31	0.73
Cesarean birth		−0.01	−0.24, 0.26	0.94
Private Insurance		0.22	0.003, 0.45	0.05
Base excess		0.01	−0.01, 0.04	0.34
NICU morbidity		0.05	−0.22, 0.33	0.68
Caffeine Treatment		0.29	0.02, 0.56	0.04*