Surprisingly, a lot of women get pregnant that soon after, and even sooner. I know two women who were already pregnant at their 6 week PP check up. Eek! It really depends on your health, your body, YOU in general. It isn't the same for everyone, but more often then not, things are fine and the pregnancy is fine.
Good luck, though! My daughter just turned 5 months, I can't imagine being pregnant again. I'd probably die lol.