I really wouldn't if I was you. Restricting your food intake is potentially hazardous to you and your developing baby.
You need:
About 1,800 calories per day during the first trimester
About 2,200 calories per day during the second trimester
About 2,400 calories per day during the third trimester
As long as you're not going stupidly crazy over these guidelines then you should certainly not reduce your calorie intake.
Why don't you get a calorie counter app on your phone and monitor what you're having during a day.