There's no real evidence that says 5 meals a day is better than 3 meals a day -or that it helps you lose weight.
Since you're pregnant - now is the time to make sure you are eating as healthy as possible,
dieting is probably not the best thing for you - however do keep in mind that you are eating for 2 - just not 2 full grown men -that which is growing inside of you is about the size of a pea right now...
Talk to your health care professional about what you should or shouldn't be eating (I've read all sorts of do's and don't's for pregnant types...) and if you haven't been working out - start slowly and do talk to your doctor again about what's appropriate...
What are your current stats - -height/weight/age - etc..