I had my daughter (who is now 8mths) when I had a BMI of 27 and I was in the middle of my weight loss. I had already gone from 16st5 down to 12st5 when she was conceived. After birth the weight was about the same.
If you eat healthy most of the time you wont gain excess weight from your pregnancy as I only put on 1.5 stone for the whole pregnancy. And I had a lot of McDonalds. We are now trying for our third (or about to) so you go for it.
I would just advise against trying if you are obese as it is too much pressure on your body and you can end up with diabetes, high blood pressure etc.
Best of luck