Is smoking marijuana during pregnancy illegal?

My husbands brother has a girlfriend who smoked pot throughout her pregnancy. She was suspended for failing her ua at her job at 8 months pregnant. Now currently they both smoke around their child and leave it laying around. I seen her playing with buds and i was freaking out because kids always put stuff in their mouths. They even drive their child while they are high. The girlfriend is currently pregnant again now and we are pretty sure shes smoking still. When we spend time with them they have it laying around everywhere and have seen the toddler playing with it and they didnt care. My husband and I dont smoke and we aren't totally against marijuana for some cases but isnt this a little extreme? Even a health hazard for their toddler and new baby coming? My husband wanted to turn them in for exposing their toddler and their soon to be newborn for it. They dont see anything wrong with it and think it's not a health issue we are just stuck up. Looking for an opinion on this. Thanks!