Early exposure to animals and childhood body mass index percentile and percentage fat mass

Figures & data

Figure 1. ECHO cohort flow chart, United States, 2017–2019, ages 4 to 8.

832 children had in-person visits, but one did not have their weight measured, so n = 831 have BMI.

Table 1. Description of all variables considered, total and by child BMI percentile status, United States, 2017–2019, ages 4 to 8

	All children, N = 831, N (%) or Mean ± SD	Normal BMI, n = 589, N (%) or Mean ± SD	Overweight BMI, n = 134, N (%) or Mean ± SD	Obese BMI, n = 108, N (%) or Mean ± SD	p-value
Early exposure to animals (dog/farm, n = 770)					0.01
Yes	245 (31.8%)	190 (34.5%)	36 (29.8%)	19 (19.4%)
No	525 (68.2%)	361 (65.5%)	85 (70.3%)	79 (80.6%)
Child age^a (years, n = 831)	6.8 ± 1.0	6.8 ± 1.0	6.8 ± 1.0	6.9 ± 0.9	0.70
Child gender (n = 831)					0.99
Female	402 (48.4%)	286 (48.6%)	64 (47.8%)	52 (48.2%)
Male	429 (51.6%)	303 (51.4%)	70 (52.2%)	56 (51.9%)
Child race/ethnicity (n = 831)					<.001
Asian/Pacific Islander	105 (12.6%)	91 (15.5%)	11 (8.2%)	3 (2.8%)
Hispanic	241 (29.0%)	139 (23.6%)	49 (36.6%)	53 (49.1%)
Non-Hispanic Black	263 (31.7%)	183 (31.1%)	41 (30.6%)	39 (36.1%)
Non-Hispanic White	222 (26.7%)	176 (29.9%)	33 (24.6%)	13 (12.0%)
Received food assistance (n = 816)					<.001
Yes	515 (63.1%)	343 (59.2%)	81 (61.8%)	91 (85.9%)
Never	301 (36.9%)	236 (40.8%)	50 (38.2%)	15 (14.2%)
Maternal education (n = 831)					<.001
Up to HS graduate	197 (23.7%)	117 (19.9%)	40 (29.9%)	40 (37.0%)
Beyond HS	634 (76.3%)	472 (80.1%)	94 (70.2%)	68 (63.0%)
Dog in home for first year (n = 771)					0.01
Yes	237 (30.7%)	184 (33.3%)	35 (28.9%)	18 (18.4%)
No	534 (69.3%)	368 (66.7%)	86 (71.1%)	80 (91.6%)
Cat in home for first year (n = 768)					0.91
Yes	94 (12.2%)	69 (12.6%)	14 (11.6%)	11 (11.2%)
No	674 (87.8%)	480 (87.4%)	107 (88.4%)	87 (88.8%)
Farm animals in first year (n = 770)					0.83
Yes	14 (1.8%)	11 (2.0%)	1 (0.8%)	2 (2.0%)
No	756 (98.2%)	540 (98.0%)	120 (99.2%)	96 (98.0%)
Dog in home in past 12 months (n = 769)					0.42
Yes	286 (37.2%)	207 (37.6%)	48 (40.0%)	31 (31.6%)
No	483 (62.8%)	344 (62.4%)	72 (60.0%)	67 (68.4%)
Cat in home in past 12 months (n = 767)					0.31
Yes	94 (12.3%)	73 (13.3%)	13 (10.7%)	8 (8.2%)
No	673 (87.7%)	475 (86.7%)	108 (89.3%)	90 (91.8%)
Maternal pre-pregnancy BMI (kg/m^2, n = 823)	25.8 ± 5.5	25.1 ± 5.2	26.7 ± 5.3	29.1 ± 6.4	<.001
Parity (n = 831)					0.46
Primiparous	378 (45.5%)	276 (46.9%)	56 (41.8%)	46 (42.6%)
Multiparous	453 (54.5%)	313 (53.1%)	78 (58.2%)	62 (57.4%)
Delivery mode (N = 830)					0.26
C-section	264 (31.8%)	177 (30.1%)	48 (35.8%)	39 (36.1%)
Vaginal	566 (68.2%)	411 (69.9%)	86 (64.2%)	69 (63.9%)
NICU admission (n = 828)					0.19
Yes	104 (12.6%)	67 (11.4%)	23 (17.2%)	14 (13.0%)
No	724 (87.4%)	519 (88.6%)	111 (82.8%)	94 (87.0%)
Breastfed exclusively ≥6 months (n = 782)					0.001
Yes	170 (21.7%)	141 (25.1%)	19 (15.3%)	10 (10.4%)
No	612 (78.3%)	421 (74.9%)	105 (84.7%)	26 (89.6%)
Age began daycare/school (n = 772)					0.03
Before 1 year	442 (57.3%)	321 (58.1%)	57 (47.5%)	64 (64.7%)
1 year or older	330 (42.8%)	232 (42.0%)	63 (52.5%)	35 (35.4%)
Antibiotic prescriptions (n = 770)					0.97
0	183 (23.8%)	134 (24.1%)	26 (22.8%)	23 (22.8%)
1–2	227 (29.5%)	165 (29.7%)	31 (27.2%)	31 (30.7%)
3–4	163 (21.2%)	117 (21.1%)	27 (23.7%)	19 (18.8%)
5+	197 (25.6%)	139 (25.1%)	30 (26.3%)	28 (27.7%)
Child activity (n = 805)					0.10
Lower	307 (38.1%)	209 (36.2%)	49 (39.5%)	49 (47.1%)
Higher	498 (61.9%)	368 (63.8%)	75 (60.5%)	55 (52.9%)

SD = standard deviation. Percentages may not sum to 100 due to rounding.

^aOne child was 9.0 years of age.

Chi-square (or Fisher’s Exact test) was used to compare categorical variables by BMI categories, and Kruskal-Wallis test was used to compare continuous variables by BMI categories.

Table 2. Multinomial logistic regression with 3 categories of child BMI percentile as outcome, with and without multiple imputation, United States, 2017–2019, ages 4 to 8

	Model 1, N = 681 OR (95% CI)	Model 1a^a, N = 831 OR (95% CI)
Early exposure to animals (dog/farm)
Overweight	0.84 (0.52, 1.36)	0.75 (0.47, 1.19)
Obese	0.53 (0.28, 0.997)	0.54 (0.30, 0.95)
Child race/ethnicity (ref = Non-Hispanic White)
Asian/Pacific Islander overweight	0.63 (0.27, 1.44)	0.64 (0.30, 1.38)
Asian/Pacific Islander obese	0.31 (0.06, 1.47)	0.41 (0.11, 1.54)
Non-Hispanic Black overweight	1.46 (0.74, 2.87)	1.34 (0.72, 2.52)
Non-Hispanic Black obese	1.60 (0.67, 3.80)	1.51 (0.67, 3.40)
Hispanic overweight	1.95 (1.02, 3.73)	2.01 (1.11, 3.63)
Hispanic obese	2.79 (1.21, 6.42)	3.08 (1.42, 6.68)
Less active child
Overweight	1.30 (0.83, 2.05)	1.30 (0.86, 1.97)
Obese	2.09 (1.24, 3.53)	2.03 (1.27, 3.24)
Received food assistance
Overweight	0.73 (0.43, 1.25)	0.67 (0.41, 1.10)
Obese	2.05 (0.97, 4.30)	2.19 (1.09, 4.37)
Started daycare at <1 year
Overweight	0.65 (0.42, 1.00)	0.59 (0.40, 0.89)
Obese	1.37 (0.80, 2.34)	1.36 (0.84, 2.22)
Maternal pre-pregnancy BMI
Overweight	1.06 (1.02, 1.10)	1.05 (1.01, 1.09)
Obese	1.10 (1.06, 1.15)	1.10 (1.06, 1.14)
Not exclusively breastfed x6 months
Overweight	1.67 (0.94, 2.96)	1.70 (0.99, 2.92)
Obese	1.97 (0.92, 4.21)	2.01 (0.99, 4.08)
Admitted to NICU after birth
Overweight	1.85 (1.04, 3.28)	1.59 (0.93, 2.72)
Obese	0.99 (0.47, 2.09)	0.92 (0.47, 1.80)

OR = odds ratio, CI = confidence interval

All variables listed are adjusted for all other variables.

^aModel included multiple imputation. Variables used for imputation included all variables in the final model as well as auxiliary variables for mother’s reported current BMI, income during pregnancy, parity at pregnancy, pregnancy work status, time spent playing with a pet while pregnant, maternal education, dog ownership in the prior year, child’s current difficulty sleeping, and presence of TV in child’s bedroom.

Table 3. Multivariable linear regression with continuous percent fat mass as outcome, United States, 2017–2019, ages 4 to 8

	Model 2, N = 548 β estimates (95% CI)	Model 2a^a, N = 611 β estimates (95% CI)
Early exposure to animals (dog/farm)	−1.55 (−2.99, −0.11)	−1.48 (−2.88, −0.09)
Child race/ethnicity (ref = Non-Hispanic White)
Asian/Pacific Islander	3.00 (0.86, 5.14)	2.85 (0.75, 4.95)
Non-Hispanic Black	−2.86 (−4.82, −0.90)	−2.49 (−4.39, −0.58)
Hispanic	1.08 (−0.88, 3.03)	1.11 (−0.77, 2.99)
Less active child	2.69 (1.34, 4.05)	2.74 (1.43, 4.06)
Received food assistance	3.05 (1.42, 4.69)	3.05 (1.47, 4.63)
Maternal pre-pregnancy BMI (per kg/m^2)	0.24 (0.13, 0.36)	0.26 (0.15, 0.38)
Not exclusively breastfed x6 months	1.46 (−0.08, 3.01)	1.43 (−0.09, 2.95)
No maternal education beyond high school	2.08 (0.33, 3.84)	1.59 (−0.03, 3.22)

CI = confidence interval

All variables listed are adjusted for all other variables.

^aModel included multiple imputation. Variables used for imputation included all variables in the final model as well as auxiliary variables for mother’s reported current BMI, income during pregnancy, pregnancy work status, time spent playing with a pet while pregnant, dog ownership in the prior year, age of child, presence of TV in child’s bedroom, and presence of biological father in home during pregnancy.