“The article suggests that cannabis use during pregnancy predicts offspring developing schizophrenia, and that this is strong evidence that cannabis is causing the increased risk of schizophrenia. While it may be the case that cannabis use increases the risk of schizophrenia, this new research is not stronger evidence of a causal link.

A person who chooses to use cannabis is likely to be different from a person who chooses not to in many ways, and these differences could be causing the increased risk for schizophrenia rather than the use of cannabis itself. But this is also true for women who choose to use cannabis while pregnant. These women are also going to be different in other ways from women who do not use cannabis (for example they may be more likely to smoke tobacco) and the environment their child grows up in could be the risk factor for schizophrenia, rather than the cannabis use.”