Objective To assess the quality, biases, and validity of evidence on maternal paracetamol (acetaminophen) use during pregnancy and the risk of autism spectrum disorder (referred to as autism) and attention deficit/hyperactivity disorder (ADHD) in offspring. Design Umbrella review of systematic reviews. Data sources Medline, Embase, PsycINFO, and the Cochrane Database of Systematic Reviews, along with grey literature, Epistemonikos, and the reference lists of included studies (inception to 30 September 2025). Inclusion criteria Systematic reviews of randomised trials and cohort, case-control, or cross sectional studies that reported maternal paracetamol use during pregnancy and the diagnosis of autism or ADHD in offspring. Details of the primary studies included in the reviews are reported, including adjustments for key confounders (maternal characteristics, indication for paracetamol use, and familial factors) and unmeasured confounders and ascertainment of outcomes. Results Nine reviews (40 studies) reporting on autism (six studies) and ADHD (17 studies) in offspring were included. Four reviews undertook meta-analysis. The overlap of primary studies included in the reviews was very high (corrected covered area 23%). The reviews reported a possible to strong association between maternal paracetamol intake and autism or ADHD or both in offspring. Seven of the nine reviews advised caution when interpreting the findings owing to the potential risk of bias and confounding in the included studies. Confidence in the findings of the reviews was low (two reviews) to critically low (seven reviews) based on the AMSTAR 2 (A MeaSurement Tool to Assess Systematic Reviews) criteria. Only one review included studies (n=2) reporting autism and ADHD in offspring that appropriately adjusted for familial factors and unmeasured confounding through sibling controlled analyses. In both studies, the increased risk of autism in offspring (one study, hazard ratio 1.05, 95% confidence interval 1.02 to 1.08) and ADHD (two studies, 1.07, 1.05 to 1.10 and 2.02, 1.17 to 3.25 ) observed in the whole cohort analyses did not persist in sibling controlled analyses for autism (0.98, 0.93 to 1.04) and ADHD (0.98, 0.94 to 1.02 and 1.06, 0.51 to 2.05). Conclusion Existing evidence does not clearly link maternal paracetamol use during pregnancy with autism or ADHD in offspring. Systematic review registration PROSPERO CRD420251154052. All data relevant to the study is included in the article or uploaded as supplementary information.