Table 1 Descriptive statistics of participant characteristics _a

Child Age, y

3.46 ± 1.13

3.48 ± 0.01

3.76 ± 1.03

3.69 ± 0.10

1.94

34998

0.05

Child Sex

31.02

34999

< 0.001

Male

17674 (51.33%)

50.6% (49.4% − 52.0%)

484 (78.57%)

75.4% (66.3% − 83.0%)

Female

16760 (48.67%)

49.4% (48.2% − 51.0%)

132 (21.43%)

24.6% (17.4% − 34.0%)

Ethnic group

5.15

34997

< 0.01

White

26539 (77.07%)

67.7% (66.5% − 69.0%)

429 (69.64%)

57.9% (48.8% − 66.0%)

Black or American

2065 (6.00%)

12.6% (11.7% − 13.0%)

61 (9.90%)

20.5% (13.5% − 30.0%)

American Indian or Alaska native

263 (0.76%)

1.6% (1.2% − 2.0%)

5 (0.81%)

0.3% (0.1% − 1.0%)

Other

5567 (16.17%)

18.1% (17.1% − 19.0%)

121 (19.64%)

21.3% (14.8% − 30.0%)

Highest educational level in the household^b

7.47

34996

< 0.001

Less than high school

602 (1.75%)

6.4% (5.6% − 7.0%)

22 (3.57%)

10.5% (6.0% − 18.0%)

High school

3703 (10.75%)

18.2% (17.1% − 19.0%)

95 (15.42%)

25.8% (18.2% − 35.0%)

Some college or Associate Degree

7195 (20.90%)

21.2% (20.3% − 22.0%)

171 (27.76%)

30.5% (22.6% − 40.0%)

College degree or higher

22849 (66.36%)

53.9% (52.7% − 55.0%)

328 (53.25%)

33.2% (26.8% − 40.0%)

Maternal age when giving birth^c

0.48

34997

0.70

≤ 25 years

6625 (19.24%)

23.2% (22.2% − 24.0%)

132 (21.43%)

24.7% (17.1% − 34.0%)

> 25–35 years

21600 (62.73%)

58.0% (56.8% − 59.0%)

359 (58.28%)

56.9% (48.0% − 65.0%)

> 35 years

5803 (16.85%)

17.2% (16.3% − 18.0%)

116 (18.83%)

15.2% (10.8% − 21.0%)

Family income, % FPL

6.07

34997

< 0.001

0–99

3275 (9.51%)

17.3% (16.2% − 18.0%)

109 (17.69%)

26.4% (19.5% − 35.0%)

100–199

5666 (16.45%)

22.4% (21.3% − 24.0%)

136 (22.08%)

33.9% (25.1% − 44.0%)

200–399

12170 (35.34%)

32.1% (31.0% − 33.0%)

210 (34.09%)

22.4% (17.3% − 28.0%)

≥ 400

13323 (38.69%)

28.2% (27.3% − 29.0%)

161 (26.14%)

17.3% (13.0% − 23.0%)

Low birth weight^d

1.98

34998

0.14

Yes

2672 (7.76%)

8.7% (8.0% − 9.0%)

80 (12.99%)

14.6% (9.7% − 22.0%)

No

30849 (89.59%)

87.7% (86.8% − 88.0%)

520 (84.42%)

82.2% (75.0% − 88.0%)

Preterm birth^e

3.83

34998

0.02

Yes

3481 (10.11%)

11.1% (10.3% − 12.0%)

110 (17.86%)

18.1% (13.3% − 24.0%)

No

30718 (89.21%)

88.1% (87.2% − 89.0%)

498 (80.84%)

79.9% (73.4% − 85.0%)

Only child

4.44

34999

0.04

Yes

22326 (64.84%)

21.8% (21.0% − 23.0%)

359 (58.28%)

30.7% (23.3% − 39.0%)

No

12108 (35.16%)

78.2% (77.3% − 79.0%)

257 (41.72%)

69.3% (60.7% − 77.0%)

Breastfeeding Duration in Categories

1.70

34996

0.15

Never

5665 (16.82%)

21.5% (20.4% − 23.0%)

144 (23.68%)

31.0% (22.7% − 41.0%)

> 0–6 months

11609 (34.46%)

34.7% (33.5% − 36.0%)

241 (39.64%)

35.7% (28.2% − 44.0%)

> 6–12 months

8473 (25.15%)

22.6% (21.6% − 24.0%)

102 (16.78%)

17.0% (11.7% − 24.0%)

> 12–24 months

6573 (19.51%)

17.7% (16.8% − 19.0%)

96 (15.79%)

13.7% (9.2% − 20.0%)

> 24 months

1370 (4.07%)

3.6% (3.2% − 4.0%)

25 (4.11%)

2.6% (1.4% − 5.0%)

Ever Breast-fed

3.81

34999

0.05

No

5665 (16.45%)

21.1% (20.0% − 22.0%)

144 (23.38%)

30.8% (22.5% − 41.0%)

Yes

28769 (83.55%)

78.9% (77.9% − 80.0%)

472 (76.62%)

69.2% (59.4% − 77.0%)

Breastfeeding Status

2.70

34998

0.07

No Breastfeeding

5665 (16.45%)

21.1% (20.0% − 22.0%)

144 (23.38%)

30.8% (22.5% − 41.0%)

Partial Breastfeeding

25425 (73.84%)

69.0% (67.9% − 70.0%)

410 (66.56%)

57.3% (48.2% − 66.0%)

Exclusive Breastfeeding

3344 (9.71%)

9.9% (9.2% − 11.0%)

62 (10.06%)

11.8% (7.3% − 19.0%)