I can imagine it to be quite hard. However, I do think that it is possible to do studies that meet the 'good enough' criteria and that certain key points can be

I can imagine it to be quite hard. However, I do think that it is possible to do studies that meet the 'good enough' criteria and that certain key points can be ascertained with high confidence (e.g. taking folic acid at the beginning of a pregnancy/before conception - don't drink alcohol, etc). The issue I'm finding is that most books for parents seem to be a collection of anecdote and personal bias. It would be nice to have a book which provides references and true insight.