Find maternity nightwear from designers including HotMilk, Amoralia and Melba Maternity. There are mix and match sets such as the Soft collection from Melba Materity (see for example the navy maternity PJ's), as well as super soft bamboo maternity pyjamas by Amoralia.
All the maternity pyjamas and nightdresses are desiged for breastfeeding too, and also make great maternity loungewear before and after baby's born.