Breastfeeding and autism spectrum disorder: case-control study

this is a case-control study carried out in the north of the state of Minas Gerais, Brazil, which included 248 children and adolescents diagnosed with ASD (case group) and 886 children and adolescents without a diagnosis of ASD (control group).Interviews were conducted with the mothers of children and adolescents and a semi-structured questionnaire was used to collect data. For data analysis, a multiple logistic regression model was adopted. The magnitude of associations was estimated by the odds ratio (OR). Three multiple models were fitted: Model 1: presence or absence of breastfeeding; Model 2: duration of breastfeeding; Model 3: duration of exclusive breastfeeding.

Results:

ASD was associated with the absence of breastfeeding in the three adjusted models: Model 1: OR=2.1, CI95%=1.1-4.1; Model 2: OR=2.3, CI95%=1.2-4.5; Model 3: OR=2.3, CI95%=1.2-4.5.

Conclusions:

individuals with ASD were more likely to have not received breastfeeding, however, due to the nature of case control studies, it cannot be stated that breastfeeding prevents ASD. Conducting a cohort study may clarify this relationship.

Key words
Breast feeding; Autism spectrum disorder; Observational study; Odds ratio

Variables	Case (N=248)		Control (N=886)		Total (N=1134)		p^ * Chi-square test; ASD= autism spectrum disorder.*
Variables	n	%	n	%	n	%	p^ * Chi-square test; ASD= autism spectrum disorder.*
Gender of the children/adolescent							<0.001
Female	47	19.0	437	49.3	484	42.7
Male	201	81.0
Prematurity (weeks)							0.054
≥ 37	194	81.5	731	86.8	925	86.1
< 37	44	18.5	111	13.2	155	13.9
Twin pregnancy							0.013
No	235	94.8	866	97.7	1101	97.1
Yes	13	5.2	20	2.4	33	2.9
Presence of crying at birth							<0.001
Yes	205	82.7	823	92.9	1028	90.7
No	43	17.3	63	7.1	106	9.3
Presence of meconium							<0.001
Yes	47	19.0	89	10.0	136	12.0
No	201	81.0	797	90.0	998	88.0
Hospitalization at NICU							<0.001
Yes	42	16.9	62	7.0	104	9.2
No	206	83.1	824	93.0	1030	90.8
Family History of ASD							<0.001
Yes	51	20.6	56	6.3	107	9.4
No	197	79.4	830	93.7	1027	90.6
Mother’s age at birth (years)							<0.001
< 25	46	18.5	293	33.1	339	29.9
25 - 34	148	59.7	437	49.3	585	51.6
≥ 35	54	21.8	156	17.6	210	18.5
Socioeconomic class							0.320
A or B	149	60.1	493	56.2	642	57.1
C	87	35.1	351	40.0	438	38.9
D or E	12	4.8	33	3.8	45	4.0
Skin color of mother							0.001
Non-white	180	73.2	716	82.8	916	81.0
White	66	26.8	149	17.2	215	19.0

Breastfeeding	Model 1
Breastfeeding	OR_a (CI95%)	p
Yes	1.00
No	2.1 (1.1-4.1)	0.025 X²2 Li Q, Li Y, Liu B, Chen Q, Xing X, Xu G, et al. Prevalence of Autism Spectrum Disorder Among Children and Adolescents in the United States From 2019 to 2020. JAMA Pediatr. 2022 Sep; 176 (9): 943-5._HL = 0.688; Pseudo R²_N =0.245
Duration of breastfeeding	Model 2
Duration of breastfeeding	OR_a (CI95%)	p
6 months	1.00
> 6 months	0.8 (0.5-1.3)	0.347
< 6 months	1.2 (0.8-1.8)	0.278
Do not remember	0.9 (0.4-2.2)	0.797
Did not breastfeed	2.3 (1.2-4.5)	0.016 X²2 Li Q, Li Y, Liu B, Chen Q, Xing X, Xu G, et al. Prevalence of Autism Spectrum Disorder Among Children and Adolescents in the United States From 2019 to 2020. JAMA Pediatr. 2022 Sep; 176 (9): 943-5._HL = 0.513; Pseudo R²_N =0.247
Duration of exclusive breastfeeding	Model 3
Duration of exclusive breastfeeding	OR_a (CI95%)	p
6 months	1.00
> 6 months	0.8 (0.4-1.4)	0.339
< 6 months	1.3 (0.9-1.8)	0.236
Do not remember	0.9 (0.5-1.8)	0.823
Did not breastfeed	2.3 (1.2-4.5)	0.014 X²2 Li Q, Li Y, Liu B, Chen Q, Xing X, Xu G, et al. Prevalence of Autism Spectrum Disorder Among Children and Adolescents in the United States From 2019 to 2020. JAMA Pediatr. 2022 Sep; 176 (9): 943-5._HL = 0.552; Pseudo R²_N =0.247

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[1] Associated Editor: Lygia Vanderlei