Cot death advice ligic

[MacMomo]

My leaflet on preventing cot death says not to put baby on a cushion or pillow. Does anyone know why? Is it because they need a firm mattress underneath and a cushion isn't firm enough? Would a very firm one then be ok? Mum just had my newborn on a very firm large cushion. Is that ok? Nervous new mum here!

its more a suffocation and overheating risk than to do with firmness

both my boys have had plenty of naps when tiny on cushions and sofas, and slept on our bed with several pillows and a big thick duvet. ventilation is my main concern so if the room is really warm and stuffy then i wouldn't let them sleep there. i also tended to do the besotted mum routine of watching them sleep.