Table 2.

Bivariate relationships between predictor variables and breastfeeding initiation and lactation score

Variable	Initiation of breastfeeding (n = 450)		Lactation score* (n = 274)
	%	P-value**	Mean (SD)	P-value**
Age
18–24	45.3	<0.0001	8.2 (6.5)	0.02
25–34	74.5		13.0 (7.8)
35+	69.6		12.3 (8.0)
Race
White/other	76.5	0.0001	14.0 (7.9)	<0.0001
Black	59.6		9.8 (6.9)
Education
High school graduate or less	59.1	<0.0001	10.5 (7.9)	0.003
College degree	70.0		12.7 (7.7)
Postgraduate degree	87.6		14.5 (7.5)
Marital status
Single	53.2	<0.0001	9.1 (6.3)	0.0001
Married	76.1		13.4 (8.0)
Plan to work outside home (at 6 mo pp)
Not work outside the home	76.7	0.14	16.1 (7.9)	<0.0001
Parttime	71.6		13.5 (8.7)
Fulltime	66.0		10.8 (7.0)
Parity
1	68.1	0.03	11.3 (7.9)	0.16
2	63.6		12.8 (7.9)
3+	78.6		13.6 (7.6)
Current smoking
No	70.5	0.003	12.6 (7.8)	0.007
Yes	42.3		5.6 (5.3)
Postpartum depression
No	69.6	0.30	12.4 (7.8)	0.66
Yes	61.5		11.6 (8.4)
Delivery type
Vaginal	70.8	0.21	12.6 (7.9)	0.48
Cesarean section	65.1		11.9 (7.7)
Preterm birth (<37 weeks)
No	71.3	0.005	12.6 (7.8)	0.12
Yes	51.9		9.6 (8.4)
Gestational weight gain [24]
Under IOM recommendations	65.9	0.56	11.8 (7.5)	0.52
Within IOM recommendations	73.1		13.4 (8.0)
Above IOM recommendations	68.5		12.2 (7.9)
Body mass index (kg/m2) [23]
25–29.9 (overweight)	75.0	0.003	14.0 (7.9)	0.004
30–34.9 (obese class I)	72.3		10.9 (7.6)
35–39.9 (obese class II)	60.0		13.1 (7.9)
40+ (obese class III)	52.5		9.1 (6.8)

Significant P-values in bold

^*Range = 1–24

^**Chi-square test for differences in proportions; ANOVA and t-tests for differences in means