To lose weight before baby #2?

DH & I just decided to start trying for #2 after our first turned 2 yrs old. Unfortunately, I had a doctor tell me my BMI was too high. I'm about 10 lbs into the "overweight" category. I work out 5x a week and eat pretty well but I was wondering: should I work really hard to lose those last 10 lbs before trying for baby #2? Even if I'm just gonna gain it back during pregnancy? I'm already thinner than when I got pregnant the first time.