Statistically there is no difference in the average levels of ergothioneine (a metabolite in mushrooms) between those who develop pre-eclampsia and those who do not. However, if your levels are above the 90th percentile your chances of developing it are negligible, implying a protective effect – read more from Kell and colleagues in the ‘Relationship between the concentration of ergothioneine in plasma and the likelihood of developing pre-eclampsia’.