I was 125 pounds when I got pregnant with my oldest. I was 150 pounds when she was born. I was 145 pounds when I got pregnant with my twins (5 months after my oldest was born). They were born 18 months ago, and I am still 140 pounds.
I don't think my body wants to let go of this weight, but I'm not sweating it too much. My weight is within the normal range for my height.
Don't diet while pregnant. Just eat healthy foods and get adequate exercise and sleep.