Hi tellytubby-
Resricting food intake whilst pregnant is not the best idea, although the quality of food you eat during pregnancy can have a dramatic effect on the amount of weight you gain (and subsequently lose) during and after pregnancy.
The best advice I can give you is to read the book The Natural Way to Better Babies by Francesca Naish (avail online) - its a brilliant guide for anyone who is pregnant!! It has advice for much more than just the optimum diet for pregnancy - such as how to reduce the risk of birth defects, low birth weight, premature birth, post-natal depression etc. Following guidelines such as this during and after pregnancy will ensure that your body responds in the best possible manner to your weight loss attempts after the pregnancy. Oh - and don't forget breastfeeding - nothing beats that for a metabolism boost!!

Best of luck to you...

XX