Table 3.

Comparisons by mean difference of serum copper and zinc levels, for the intervention and control groups, on days 1 and 21 of the clinical trial.

Variable	Comparisons	Mean difference	p-value	CI 95 % LL	CI 95 % UL
Copper	A – B (D1)	−45,6	0,47	−171.4	80,1
	A – B (D21)	−67,7	0,28	−193.5	58,1
	D1 - D21 (A)	78,0	0,11	−19.1	175,1
	D1 - D21 (B)	55,9	0,25	−41.2	153,1
Zinc	A – B (D1)	−33,5	0,57	−150.8	83,8
	A – B (D21)	58,2	0,32	−59.1	175,6
	D1 - D21 (A)	149,5	<0,01	67.0	231,9
	D1 - D21 (B)	241,2	<0,01	158.7	323,7

D1, first day of the study; D2, twenty-first day of the study; Lioneo group (A), newborns who received human milk with a human milk-based additive; HMCA group (B), newborns who received human milk with a cow milk protein-based additive; 95 % CI, 95 % confidence interval; LL, lower limit; UL, upper limit.