I am in the weight management industry and we have specialised programs for pregnant women... it is usual to put on between 10-15kg whilst pregnant. It is not safe to activly try to loose weight whilst pregnant any other way apart from with DR/OB or a specialised clinic. As has been said, water retention can be a major reason why you put on more than 'baby weight'. make sure you drink plenty of water and rest for half an hour with legs elevated after being on feet for over two hours.. especially later on....
we have been TTC for 6 months now and i thought i might pop in a have a look at what goes on once we get our BFP!