Table 2 Results of stepwise multiple regression analysis in preterm infants; dependent variable is carotid flow.

Independent variable	Simple correlation coefficient	Partial correlation coefficient	Regression coefficient	Confidence interval (95%)
Day	0.41**	0.44**	0.16	0.056 to 0.27
Gestation (weeks)	0.61**	−0.13	Excluded from model
Weight (kg)	0.64**	0.65**	13.6	8.49 to 18.70
Cardiac output (ml/min)	0.59**	−0.20	Excluded from model
Intercept	–	–	5.72	−2.12 to 13.56

Although all the independent variables were associated with carotid flow in simple correlation, multiple regression analysis showed that only weight and age in days were independently associated with carotid flow.

**p<0.01.