Table 1.

Characteristics of mothers in the derivation and validation cohorts with complete information on the four questions included in the breastfeeding score.

Characteristics	Derivation Cohort 1999	Validation Cohort 2004	p Value *	Validation Cohort 2017	p Value *
	n = 391	n = 633		n = 579
	n (%)	n (%)		n (%)
Sociodemographic Factors
Maternal age: How old are you?
17–23	36 (9)	43 (7)	0.32	34 (6)	0.002
24–31	245 (63)	391 (62)		323 (56)
>32	109 (28)	196 (31)		222 (38)
Vocational Education: Which vocational education have you completed?
None–short-skilled	256 (65)	373 (59)	0.04	195 (34)	<0.001
Theoretical bachelor–master	135 (35)	260 (41)		384 (66)
Smoking: Do you smoke now after giving birth?
Yes	78 (20)	113 (18)	0.40	33 (6)	<0.001
No	313 (80)	520 (82)		546 (94)
Perinatal factors
Parity: How many children have you given birth to?
Primipara	157 (40)	257 (41)	0.91	276 (48)	0.02
Multipara	233 (60)	376 (59)		303 (53)
Previous breastfeeding experience: How many weeks did you breastfeed your previous child without giving it anything else?
None, primipara	157 (40)	257 (41)	0.09	276 (48)	<0.001
0–5 weeks	31 (8)	40 (6)		70 (12)
6–17 weeks	104 (27)	137 (22)		83 (14)
>17 weeks	99 (25)	199 (31)		150 (26)
Psychosocial factors
Self-efficacy with respect to breastfeeding: How certain are you that you can complete four months of exclusive breastfeeding
Medium to very uncertain (1–3)	131 (33)	153 (24)	<0.001	189 (33)	0.78
Certain to very certain (4–5)	260 (67)	480 (76)		390 (67)
Sense of security not knowing the exact amount of milk the baby ingests: I feel fine about not knowing exactly how much milk my child gets when being breastfed
Is not true (1–2)	181 (46)	240 (38)	0.01	246 (42)	0.24
Is fairly–exactly true (3–5)	210 (54)	393 (62)		333 (58)

Note: p value * from a comparison with derivation cohort.