Inconclusive evidence for a causal impact of maternal smoking on offspring ADHD in a Mendelian randomization study by Xie and Mao (2024)

The present simulations showed that Mendelian randomization tests, at least other than the Egger test, are susceptible to spurious findings due to confounding and do, consequently, not allow causal inference. Therefore, researchers should avoid causal language when describing results from Mendelian randomization tests. Results presented by Xie and Mao (2024) may have been due to confounding and did not provide any conclusive evidence for a causal effect of maternal smoking around birth on offspring ADHD.