Hey, I spent two evenings last week in the garden, burning wood in the incinerator (I'm not odd, we've just cut down our bushes and needed to get rid, lol), and ended up in the line of smoke a fair few times. I was worried so checked online, apparently its not fantastic for you but it should be fine in small doses. The carbon monoxide cuts down the oxygen in your bloodstream, like cigarettes. Your blood-oxygen levels go back to normal after 40 minutes, so just try to avoid it as much as possible. I would advise you either get OH to prepare dinner while the oven is smoking, or at least open the windows and make it well ventilated. Also, phone your landlord at explain that because your pregnant, him not fixing the oven is putting your unborn baby at risk, and you could actually take him to court for tenancy negligence.