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Breastfeeding May Lower Risk of ASD and ADHD

    A woman in a pink shirt holds a baby swaddled in blue in her arms. Two separate studies find that exclusively breastfeeding infants may lower their risk of ASD and ADHD, and there may be a dose-response effect.

    Written by: Brittany T. Truong, Ph.D. | Issue # 135 | 2026

    • Breastfeeding provides essential nutrients that support infant neurodevelopment. 
    • In two new studies, exclusive breastfeeding for at least 6 months was associated with a lower risk of ASD and ADHD. 
    • In both studies, there was a dose-response effect in which increasing the duration of breastfeeding further lowered children’s risk of developing ASD or ADHD. 

    Autism spectrum disorder (ASD) and attention-deficit-hyperactivity disorder (ADHD) are two neurodevelopment disorders that cause the brain to work differently. They share common traits and can often co-occur; however, they are distinct conditions [1]. 

    A child with ASD may have difficulties with social communications or interactions or have restricted or repetitive behaviors, interests, or activities [2]. In contrast, ADHD is primarily characterized by a person’s inattention, hyperactivity, and impulsivity [3]. 

    Experts recognize that both are likely caused by a combination of genetics and environmental factors, such as pregnancy complications, exposure to viruses or toxins during pregnancy, or being born too early.

    In two new observational studies, researchers have found that exclusively breastfeeding infants for at least 6 months was associated with a lower risk of ASD [4] and ADHD [5].

    The first study on ASD was an observational, cross-sectional study using publicly available data from children aged 3 to 5 in the U.S. National Survey of Children’s Health (NSCH) from 2018-2023. The researchers separated the children into four groups: never breastfed, breastfed for less than 6 months, breastfed for at least 6 months nonexclusively, and exclusively breastfed for 6 months. They performed statistical analyses, adjusting for demographic and socioeconomic factors, such as age, sex, race/ethnicity, parental education, and poverty level, and birth characteristics, including birth weight and whether the birth was premature [4]. 

    More than 48,000 children were surveyed, and approximately 3.0% (n=1469) of children had ASD. Among these, 4.0% (n=358) had never been breastfed compared with 1.8% (n=290) who were exclusively breastfed for 6 months. The researchers found that this association was dose-dependent. In other words, breastfeeding a child longer lowered the odds of having ASD [4]. 

    Children more likely to be breastfed exclusively were often non-Hispanic white, had parents with higher education, and came from higher-income families. Although the researchers adjusted their models to accommodate these factors, they note that the protective effect may have been “overestimated” [4].

    This study is consistent with previous work and meta-analyses that have suggested that breastfeeding may have a protective effect and reduce the risk of developing ASD [6]. However, earlier studies using the same database (NSCH) in children aged 2-5 years from 2007-2011 found no association [7]. Further research is required to determine the strength of this association. 

    The second study on ADHD used data from 1999 to 2008 from a population-based pregnancy cohort study called MoBa (Norwegian Mother, Father, and Child Cohort Study), which is derived from the Medical Birth Registry of Norway (MBRN). The study included data from over 37,000 children.

    In order to partially control for the heritability of ADHD, the researchers prioritized family trios in which data from the father, mother, and child at ages 3, 5, and 8 years were available. More than 18,000 trios were included. The researchers separated the children into 5 groups: no breastfeeding; partial breastfeeding for less than 4 months; partial breastfeeding for 4-6 months; exclusive breastfeeding for 4 months and partial/no breastfeeding after 4 months; exclusive breastfeeding for at least 6 months. Similar to the ASD study, the researchers adjusted for various birth characteristics and demographic and socioeconomic factors, including the parents’ polygenic risk scores for developing ADHD themselves [5]. 

    The researchers found that exclusive breastfeeding for at least 6 months was significantly associated with lower ADHD symptom scores across all ages. Moreover, the highest increase in ADHD symptom scores was observed when the mother partially breastfed for less than 4 months. The data were statistically significant after adjusting for genetic and socioeconomic factors, suggesting that breastfeeding may have a moderate protective effect against ADHD [5]. 

    This study is consistent with previous work which has shown that breastfeeding children longer may reduce the incidence of ADHD [8].

    Because these were both observational studies, the mechanism behind why breastfeeding may lower the risk of ASD and ADHD is still unclear. 

    One possible explanation is that breastfeeding may help regulate the infants’ oxytocin levels during early childhood development. Oxytocin, or the “love hormone,” is a neurotransmitter that helps with social bonding. 

    Oxytocin is released during breastfeeding and benefits both the mother and nursing infant [9]. 

    Several studies suggest that children with ASD have reduced oxytocin levels [10]. One study even found that in infants who are genetically predisposed to having lower levels of oxytocin, exclusive breastfeeding may help reduce their risk of ASD by functionally correcting their early behavior. 

    Similarly, in individuals with ADHD, misregulation of oxytocin is thought to contribute to social behaviors like impulsivity [11]. 

    Another potential mechanism could be that breast milk helps regulate the gut microbiome and lower neuroinflammation, which may be involved in both ASD and ADHD [12,13]. 

    Additional research is required to determine the mechanism of the protective effect of breastfeeding in ASD and ADHD. Regardless, both studies add to the growing body of evidence supporting the protective nature of human breast milk. 

    References

    1. ADHD vs. autism: what’s the difference? [Internet]. Cleveland (OH): Cleveland Clinic; c2026 [Cited 2026 September 24]. Available from: https://health.clevelandclinic.org/adhd-vs-autism 
    2. Autism [Internet]. Cleveland (OH): Cleveland Clinic; c2026 [Cited 2026 September 24]. Available from: https://my.clevelandclinic.org/health/articles/autism 
    3. What is ADHD? [Internet]. Washington, DC. American Psychiatric Association; c2026 [Cited 2026 September 24]. Available from: https://www.psychiatry.org/patients-families/adhd/what-is-adhd 
    4. Yuan H, Yang Z. Cross-sectional analysis of the association between exclusive breastfeeding duration and autism spectrum disorder odds in U.S. preschool children: a nationally representative study. Int Breastfeed J. 2026. https://doi.org/10.1186/s13006-026-00888-9 
    5. Solberg BS, Brantsaeter AL, Kvalvik LG, Hartman CA, Xie T, Klungsøyr K, et al. Breastfeeding and development of attention-deficit/hyperactivity disorder symptoms across childhood. Biol Psychiatry. 2026;100:725-735. 
    6. Ghozy S, Tran L, Naveed S, Quynh TT, Zayan AH, Waqas A, et al. Association of breastfeeding status with risk of autism spectrum disorder: a systematic review, dose-response analysis and meta-analysis. Asian J Psychiatr. 2020; 48:101916. 
    7. Husk JS, Keim SA. Breastfeeding and autism spectrum disorder in the National Survey of Children’s Health. Epidemiology. 2015;26(4):451-7. 
    8. Zeng Y, Tang Y, Tang J, Shi J, Zhang L, Zhu T, et al. Association between the different duration of breastfeeding and attention deficit/hyperactivity disorder in children: a systematic review and meta-analysis. Nutr Neurosci. 2020;23(10):811-23. 
    9. Moberg KU, Prime DK. Oxytocin effects in mothers and infants during breastfeeding. Infant. 2013;9(6):201-206. 
    10. John S, Jaeggi AV. Oxytocin levels tend to be lower in autistic children: a meta-analysis of 31 studies. Autism. 2021;25(8):2152-61. 
    11. Demirci E, Ozmen S, Oztop DB. Relationship between impulsivity and serum oxytocin in male children and adolescents with attention-deficit and hyperactivity disorder: a preliminary study. Noro Psikyatr Ars. 2016;53(4):291-95. 
    12. Saigh BH. Breastfeeding duration and neurodevelopment: insights into autism spectrum disorders and weaning practices. J Health Popul Nutr. 2025;44:62. 
    13. Lewis N, Villani A, Lagopoulos J. Gut dysbiosis as a driver of neuroinflammation in attention-deficit/hyperactivity disorder: a review of current evidence. Neuroscience. 2025;569:298-321.