Gap maternity sizing

[mushmaker]

Can anyone help? Going to buy a load of stuff online, what is the sizing like? I'm a pretty standard size 12. I don't usually buy anything in Gap but liked their mat stuff last time. Thanks

[Oly5]

I lived in Gap maternity and usually bought size medium for plenty of growing room, with the odd size L in cosy trousers etc (but I have a size 14 bottom and 10/12 top)