What are the pre-birth environmental risk factors for ADHD?

Read about the pre-birth factors that can increase the risk of ADHD.

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Alexandra Cristina Cowell
Medically reviewed by Alexandra Cristina Cowell Clinical Support

Reading time: 4 min

Uploaded on: January 29, 2026

Although ADHD is mostly a genetic condition, environmental factors can play a role in its development.

Factors like low birth weight, exposure to toxins and maternal stress may increase the risk of ADHD.

What pre-birth factors might have an impact?

A pregnant woman's health status can have a big impact on whether her children might get ADHD and how it will affect them.

Maternal health

Stress

Maternal stress has been associated with ADHD. 

On average, children were up to three times more likely to be diagnosed with ADHD if their mother had high stress levels during pregnancy.1 Stress can disrupt the neurodevelopment of the fetus, which increases the risk of neurological disorders like ADHD.

Stress may also continue into early childhood, which can further hinder brain development, resulting in worsened ADHD symptoms.

Low iron levels

Low iron levels during pregnancy were associated with a higher risk of ADHD. 2

Iron is needed for fetal development; without a sufficient amount, this development is altered, increasing the risk of ADHD. Low iron is also associated with dopamine and serotonin dysfunctions, two important neurotransmitters that regulate attention and focus. 3

Maternal obesity

Maternal obesity can increase the risk of ADHD in children.

While some studies suggest the risk could be as high as 92%, this is likely exaggerated, especially when accounting for genetic and family-related factors.4 Nonetheless, maternal obesity still appears to have some influence on the development of ADHD.

Smoking

Smoking during pregnancy may increase the risk of ADHD.

Early tobacco and nicotine exposure can affect brain development and functions. One study found that people whose mothers smoked during pregnancy had a smaller cerebellum volume.5 The cerebellum is the part of the brain responsible for motor and cognitive functions, including attention and emotional regulation.

Alcohol

Prenatal alcohol may increase the risk of ADHD.

Alcohol can disrupt the baby's brain development, including areas responsible for attention, memory, and behaviour — all functions related to ADHD.6

While some studies have found a weaker link between alcohol and ADHD risk or none at all, this doesn’t mean drinking during pregnancy is safe. Alcohol can still lead to other serious developmental and health problems in the child.7 9

Premature birth and low birth weight

The risk of ADHD was higher in children who had lower birth weight and were born premature.

These factors often cause development challenges, such as an underdeveloped brain, which may cause memory, attention and focus issues. It may also result in a weakened or dysregulated immune system, which may elevate ADHD risk.8

Back to:

Overview

Read next:

Post-birth factors

References:

  1. Okano, L., et al. (2018). Maternal Psychosocial Stress and Children’s ADHD Diagnosis: A Prospective Birth Cohort Study. Journal of Psychosomatic Obstetrics and Gynaecology, 40(3), 217.

  2. Schlotz, W., et al (2010). Lower maternal folate status in early pregnancy is associated with childhood hyperactivity and peer problems in offspring. Journal of Child Psychology and Psychiatry, 51(5), 594-602.

  3. Lertxundi, N., et al. (2020). Maternal Ferritin Levels during Pregnancy and ADHD Symptoms in 4-Year-Old Children: Results from the INMA–INfancia y Medio Ambiente (Environment and Childhood) Prospective Birth Cohort Study. International Journal of Environmental Research and Public Health, 17(21), 7704.

  4. Li, L., et al. (2020). Maternal pre-pregnancy overweight/obesity and the risk of attention-deficit/hyperactivity disorder in offspring: A systematic review, meta-analysis and quasi-experimental family-based study. International Journal of Epidemiology, 49(3), 857.

  5. Huang, L., et al. (2017). Maternal Smoking and Attention-Deficit/Hyperactivity Disorder in Offspring: A Meta-analysis. Pediatrics, [online] 141(1), p.e20172465.

  6. Pagnin, D., et al. (2019). Prenatal alcohol use as a risk for attention-deficit/hyperactivity disorder. European Archives of Psychiatry and Clinical Neuroscience, [online] 269(6), pp.681–687.

  7. Eilertsen, E. M., et al. (2017). Maternal alcohol use during pregnancy and offspring attention-deficit hyperactivity disorder (ADHD): A prospective sibling control study. International Journal of Epidemiology, 46(5), 1633.

  8. Ni, M., et al. (2023). Examining the relationship between birth weight and attention-deficit hyperactivity disorder diagnosis. Frontiers in Psychiatry, 14, 1074783.

  9. Haan, E., et al. (2022). Prenatal smoking, alcohol and caffeine exposure and offspring externalizing disorders: a systematic review and meta‐analysis. Addiction, 117(10).

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Reading time: 4 min

Uploaded on: January 29, 2026

Dr Daniel
Medically reviewed by Alexandra Cristina Cowell Clinical Support Registered with GMC (00001) January 29, 2026 Meet Alexandra Cristina Cowell
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Written by Focused Content Team
Last updated on May 21, 2026
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