I agree with Suzanne. If you still lose weight on 1500 calories a day at a decent pace of a pound or two a week, then there is no reason to lower it.
However, if you have stopped losing, and have not lost eating 1500 calories a day for more than a couple of weeks, then the key is to lower if gradually. Eat 1450 calories a day for a week or two, and then 1400 for a few weeks.
You may actually find that you don't need to be at 1200-1300. However, when you do drop calories, it is best to do so gradually-in smaller increments. Dropping from 1500 to 1200 is actually a pretty drastic drop!
Start weight after baby #3: 233.9
Current weight: 143
90 pounds lost!