Franziska Denk
The press release is very responsibly written and at pains to point out (correctly) that this does not yet mean that women should stop taking paracetamol when indicated during pregnancy.
It is good quality research, although it is important to point out that while 67-140 people per group seems like a lot, it is actually not such a large sample, considering that the authors measured 13 different outcomes. To have total confidence that we are not looking at chance connections, one would probably ideally have wanted more like 250-650 people per group, not 300 people in total.
The authors argue that it fits well with existing pre-clinical literature, and they see something similar in a replication cohort. One caveat to all this is that when we approach large, complex datasets with expectations in mind, it can be remarkably easy to find individual aspects that support prior work or somehow fit our expectations. These days, more and more scientists therefore try and ‘pre-register’ their analysis plans, i.e. specify ahead of time exactly what they want to do. The authors of the current study did log their trial on a repository, but the log does not contain enough statistical detail to ascertain that they did not accidentally pick up noise.
In the early life exposure group, there were a lot more smokers than in the other two groups. Smoking has a huge effect on pretty much every health outcome. This and other confounders are adjusted for in the initial cohort, but it is not clear to what extend confounders were adjusted for in the replication cohort.
Right now, I think it is too early to recommend a change in behaviour – as correctly indicated by the authors in the press release.
Pregnant women should not be worried, as very nicely laid out in the original press release.