We bought a unit/townhouse a year ago, which is one of five all attached to each other as townhouses often are. We're not terribly social and apart from the old couple on our right, haven't anything more to do with our neighbours than the standard polite smile and hello when we pass.
The couple on our left are renting, and have been here longer than us. And they love pot. If you ever wanted to scare someone off smoking pot, have them come to our house in the morning and hear the lung-and-throat destroying coughing that we are treated to. The walls are very thick and apart from the occasional high-as-a-kite singing or post 20 cans of bourbon-and-coke screaming matches (the cans end up in the communal recycling so we know their drink of choice

) we don't notice them, so the coughing has to be pretty loud.
None of this is a problem, we don't care what substances people use in their own houses, and the coughing makes us laugh. The problem is that pot smoke travels.
So we'll be in our downstairs kitchen with a window open and they'll be in their backyard and in comes the smell of pot smoke. Or we'll be upstairs watching tv with a window ajar and they'll be in their place with a window open and in comes the pot smoke. So we keep having to close our windows as we cannot stand the smell, and I'm pregnant and don't want to get inadvertantly stoned. We have recently installed new double glazed windows which have excellent insulation, but this means it can get a bit airless if we can't open a window on a warm day.
Which brings us to the crux of the matter; the impending baby. I'm 39+1 so baby will be here any second now (i hope). We had such high hopes of being able to sit in our backyard on a sunny afternoon with our LO and enjoy ourselves, or to just be able to have our windows open, but now I'm worried we'll be hiding the baby from becoming an underage stoner until our neighbours either actually cough up their lungs or leave.
I'm terrified of approaching them directly, as I find any kind of confrontation scary, and even the politest intro could be misinterpreted in this situation. I'm tempted to contact their landlord but a)don't really wish them ill and b) what would/could the landlord do anyway?
So, oh wise eb, what would you do?