I can personally say that it is a lot of work getting your body back once you’ve had a baby, I am still vigorously working at it.
When I first became pregnant I was around the 130 pound/59 kilogram mark. Definitely not the smallest I have ever been, but I was healthy and running around the 5 mile mark at the gym at least 5 days a week on a treadmill. During my pregnancy (with my now 2.5 year old Son) I put on 26 pounds/12 kilo, which I do not think is a lot? Maybe this was because I did not really get any of those weird cravings you hear pregnant women talking about like pickles and ice-cream! Either way considering diet, genetics and age, pregnancy weight gain varies from Mother to Mother. I have one friend who put on a mere 12 pounds and another who put on 90 pounds!