Boys exposed before birth to a popular pain reliever in many brands including Tylenol were more likely to have symptoms of autism during childhood, according to a new study of mothers and children in Spain.
Acetaminophen is extensively used during pregnancy. But there is a lack of population-representative cohort studies evaluating its effects on a range of neuropsychological and behavioural endpoints. We aimed to assess whether prenatal exposure to acetaminophen is adversely associated with neurodevelopmental outcomes at 1 and 5 years of age.
Acetaminophen use in pregnancy and neurodevelopment: attention function and autism spectrum symptoms, NCBI PubMed PMID: 27353198, 2016 Jun 28.
This Spanish birth cohort study included 2644 mother-child pairs recruited during pregnancy. The proportion of liveborn participants evaluated at 1 and 5 years was 88.8% and 79.9%, respectively. Use of acetaminophen was evaluated prospectively in two structured interviews. Ever/never use and frequency of use (never, sporadic, persistent) were measured. Main neurodevelopment outcomes were assessed using Childhood Autism Spectrum Test (CAST), Conner’s Kiddie Continuous Performance Test (K-CPT) and ADHD-DSM-IV form list. Regression models were adjusted for social determinants and co-morbidities.
Over 40% of mothers reported using acetaminophen. Ever-exposed offspring had higher risks of presenting more hyperactivity/impulsivity symptoms [incidence rate ratio (IRR) = 1.41, 95% confidence interval (CI) 1.01-1.98), K-CPT commission errors (IRR = 1.10, 1.03-1.17), and lower detectability scores (coefficient β = -0.75, -0.13–0.02). CAST scores were increased in ever-exposed males (β = 0.63, 0.09-1.18). Increased effect sizes of risks by frequency of use were observed for hyperactivity/impulsivity symptoms (IRR = 2.01, 0.95-4.24) in all children, K-CPT commission errors (IRR = 1.32, 1.05-1.66) and detectability (β = -0.18, -0.36-0.00) in females, and CAST scores in males (β = 1.91, 0.44-3.38).
Prenatal acetaminophen exposure was associated with a greater number of autism spectrum symptoms in males and showed adverse effects on attention-related outcomes for both genders. These associations seem to be dependent on the frequency of exposure.
Maternal use of acetaminophen during pregnancy and risk of autism spectrum disorders in childhood: A Danish national birth cohort study, NCBI PubMed PMID: 26688372, 2015 Dec 21.
And a much-publicized study last year found that women who reported using acetaminophen during pregnancy were about 50 percent more likely to have a child with autism and other behavioral issues such as hyperactivity and impulsivity.
Acetaminophen (paracetamol) is the most commonly used pain and fever medication during pregnancy. Previously, a positive ecological correlation between acetaminophen use and autism spectrum disorders (ASD) has been reported but evidence from larger studies based on prospective data is lacking.
We followed 64,322 children and mothers enrolled in the Danish National Birth Cohort (DNBC; 1996-2002) for average 12.7 years to investigate whether acetaminophen use in pregnancy is associated with increased risk of ASD in the offspring. Information on acetaminophen use was collected prospectively from three computer-assisted telephone interviews. We used records from the Danish hospital and psychiatric registries to identify diagnoses of ASD. At the end of follow up, 1,027 (1.6%) children were diagnosed with ASD, 345 (0.5%) with infantile autism.
We found that 31% of ASD (26% of infantile autism) have also been diagnosed with hyperkinetic disorders. More than 50% women reported ever using acetaminophen in pregnancy. We used Cox proportional hazards model to estimate hazard ratio (HR) and 95% confident interval (CI). Prenatal use of acetaminophen was associated with an increased risk of ASD accompanied by hyperkinetic symptoms (HR = 1.51 95% CI 1.19-1.92), but not with other ASD cases (HR = 1.06 95% CI 0.92-1.24). Longer duration of use (i.e., use for >20 weeks in gestation) increased the risk of ASD or infantile autism with hyperkinetic symptoms almost twofold.
Maternal use of acetaminophen in pregnancy was associated with ASD with hyperkinetic symptoms only, suggesting acetaminophen exposure early in fetal life may specifically impact this hyperactive behavioral phenotype.