As there was no information on thyroid hormone levels on the mothers with hypothyroidism based on hospital records,37, 50 we analysed the results from these studies separately from the study with the direct thyroid hormone measurement in participants.40 There was no statistically significant effect of maternal overt hypothyroidism based on hospital records on autism in children (OR 2.12, 95% CI 0.75 to 6.00, P = .12) (Figure S2). This evidence concerns the gene TG and hypothyroidism.