If you’re pregnant you’ve probably heard many times that you shouldn’t eat certain types of fish because they contain too much mercury. The fear is that mercury poisioning can affect a child’s mental development. In fact new research shows that mercury may be a leading cause of autism.

However, investigators seeking to measure the deleterious effects of prenatal mercury exposure were surprised to find that the children, years afterward, seemed perfectly normal.

They expected at the minimum to find developmental damage in the children of women who, when pregnant, ate fish with the highest mercury levels. But when they looked at the children years later there were almost no differences between kids whose moms had a lot of mercury in their bodies and those who moms had almost none.

As with all things though, moderation is still best. Mercury is certainly not good for you or your unborn child so don’t overdo it. But at least it’s good to know that occasionally eating fish is not harming your baby.