Table 3.

Odds of overweight at age seven and 11 years associated with prenatal antibiotics stratified by maternal pre-pregnancy BMI, cesarean section, birth weight, and sex.

	n	Unadjusted		Multivariable-adjusted
		OR (95% CI)	P value	OR (95% CI)	P value
Overweight at age seven years
Maternal pre-pregnancy BMI
Normal weight (<25 kg/m2)	27,238	1.15 (1.04–1.28)	0.007	1.08 (0.97–1.20)	0.17
Overweight (25–30 kg/m2)	6844	1.12 (0.96–1.29)	0.14	1.08 (0.93–1.25)	0.32
Obese (≥30 kg/m2)	2548	1.11 (0.91–1.35)	0.31	1.03 (0.84–1.26)	0.78
Caesarean section
No	31,640	1.21 (1.11–1.31)	<0.001	1.08 (0.99–1.17)	0.1
Yes	4990	1.17 (0.96–1.44)	0.12	0.99 (0.80–1.23)	0.95
Birth weight
<2500 g	335	1.93 (0.87–4.31)	0.11	1.53 (0.63–3.68)	0.35
2500–3999 g	27,423	1.17 (1.06–1.28)	0.002	1.04 (0.94–1.14)	0.47
≥4000 g	8872	1.24 (1.08–1.42)	0.002	1.11 (0.97–1.28)	0.13
Gender
Girl	17,804	1.15 (1.03–1.28)	0.01	1.02 (0.92–1.14)	0.69
Boy	18,826	1.27 (1.14–1.41)	<0.001	1.12 (0.99–1.25)	0.06
Overweight at age 11 years
Maternal pre-pregnancy BMI
Normal weight (<25 kg/m2)	15,897	1.15 (0.98–1.34)	0.08	1.05 (0.90–1.23)	0.52
Overweight (25–30 kg/m2)	3717	1.10 (0.90–1.33)	0.36	1.06 (0.87–1.29)	0.57
Obese (≥30 kg/m2)	1321	1.31 (1.01–1.70)	0.04	1.13 (0.86–1.48)	0.38
Cesarean section
No	18,050	1.26 (1.12–1.41)	<0.001	1.07 (0.94–1.20)	0.31
Yes	2885	1.34 (1.02–1.75)	0.04	1.04 (0.77–1.39)	0.82
Birth weight
<2500 g	186	0.74 (0.23–2.35)	0.6	0.49 (0.12–1.91)	0.3
2500–3999 g	15,655	1.22 (1.07–1.40)	0.003	1.03 (0.90–1.18)	0.67
≥4000 g	5094	1.36 (1.13–1.63)	0.001	1.15 (0.95–1.40)	0.15
Gender
Girl	10,472	1.23 (1.05–1.43)	0.009	1.04 (0.89–1.23)	0.6
Boy	10,463	1.31 (1.13–1.51)	<0.001	1.08 (0.92–1.26)	0.35

Overweight (including obesity) was defined according to age- and sex-specific criteria defined by the International Obesity Task Force. Multivariable-adjusted ORs are adjusted for maternal age at birth, maternal pre-pregnancy BMI, maternal diabetes, maternal smoking, parity, socio-economic status, gestational age at birth, and child gender.