Understanding autism
5 things about living with autism
Autism spectrum disorder (ASD), also called Autism Spectrum Condition (ASC), is a developmental condition affecting communication, social interaction, and behaviour. In the UK, about 1 in 100 people have ASD.
ASD is spectrum-based: effects vary between individuals. Some need little support, while others require substantial, long-term assistance.
Key signs of ASD, often apparent by ages 2-3, include:
• Social interaction struggles: difficulties with eye contact and nonverbal communication.
• Communication challenges: difficulty understanding sarcasm or humour and possible delayed speech.
• Repetitive behaviours: such as lining up objects or distress when routines change.
• Sensory sensitivities: aversions to certain lights, sounds, or textures.
More rarely, some people may show self-injurious behaviour, aggression, catatonia, hyperactivity, seizures, sleep problems, eating difficulties, or gastrointestinal symptoms.
The causes of ASD are complex and involve genetic and environmental factors. Family studies show higher risk among siblings, while some prenatal environmental exposures have been suggested to increase risk.
In September 2025, public attention focused on whether paracetamol (acetaminophen) use in pregnancy might increase autism risk. This has been examined in large population studies.
- The largest study to date (Sweden, 2.4 million births) initially showed a small increase in autism diagnoses among children whose mothers reported paracetamol use during pregnancy.[1]
- However, when researchers compared siblings within the same families (where one child was exposed in utero and another was not), the association disappeared.
Why sibling-comparison studies matter
Sibling-comparison (or "within-family") studies control for many shared factors, including:
- Genetic influences (siblings share about 50% of genes)
- Family environment (socio-economic circumstances, parental health behaviours, access to care)
Comparing children born to the same mother reduces the risk that an observed association is due to these shared factors. In this case, the lack of difference in sibling analyses suggests earlier links between paracetamol and autism were likely explained by the reasons for taking paracetamol - for example infection, pain, or maternal age - which are themselves associated with autism risk.
It is not known whether withholding treatment for these symptoms (for example, allowing fever or pain to escalate) could affect neurodevelopmental outcomes.
In other words, the underlying conditions are more likely to explain the association, rather than the drug itself.
Current guidance from the NHS, WHO, ACOG, and EMA remains that paracetamol can be used in pregnancy at the lowest effective dose for the shortest necessary time, and that it remains the analgesic/antipyretic of choice for pregnant patients.
References
[1] Axelsson O, Cesta CE, Iliriani K, Stephansson O, D’Onofrio BM, Hultman CM, Magnusson C, Sjölander A, Sujan AC, Öberg AS, Sandin S. Association of Acetaminophen Use During Pregnancy With Risk of Autism Spectrum Disorder in Offspring. JAMA Psychiatry. 2024;81(12):1163–1173. doi:10.1001/jamapsychiatry.2024.3594
Evidence update (2026 systematic review)
In January 2026, a large systematic review and meta-analysis of 43 cohort studies was published in The Lancet Obstetrics, Gynaecology & Women’s Health.[2] When analyses were limited to sibling-comparison studies and studies at low risk of bias, paracetamol use during pregnancy was not associated with autism, ADHD, or intellectual disability.
The authors concluded that earlier reported associations were most likely explained by confounding factors such as maternal illness, fever, pain, or genetic risk, rather than a causal effect of paracetamol itself.
[2] D’Antonio F, Flacco ME, Della Valle L, et al. Prenatal paracetamol exposure and child neurodevelopment: a systematic review and meta-analysis. The Lancet Obstetrics, Gynaecology & Women’s Health. 2026.
For clinical pharmacy staff, recognising autistic patients' communication styles, sensory sensitivities, and routine needs helps to adapt care so services are more accessible and person-centred.
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