Does anyone know about brain fluid or pregnancy?

So I’m trying to research something someone told me while I was pregnant (have a 9 month old now) but I don’t know where to begin because what was told to me was simplified.

This is what was told to me. That while pregnant a baby takes from mom’s body to get what she needs. We all know this is true that is why they tell moms to eat healthy for herself b/c baby is taking from her body whether mom is nourishing herself well or not.

So here is the rest of what I was told. That if not properly nourished a baby (or the body for the baby) will take from your brain fluid because it is really fatty and rich in nutrients. And that brain fluid can never be replenished. Haha. Of course this is oversimplified and only in very small amounts.

But does anyone have any knowledge on if this is true? Or how I would research it via the net, what search terms to use etc..?

Thanks!