I can only give you examples of family as I've not had children yet, getting and staying pregnant has been difficult for me, I'm now 40 so the chances are getting slimmer, that aside... My sister dropped the weight fast, she drank black coffee and cut her food, with her first child she had the help of my mother and I so she slept a lot, she went on to have 2 more children those kept her busy along with the food restriction and endless black coffee, I don't recommend it. She lost the weight and was back to 96 pounds in two months however she was left with saggy skin.
Now for my two cousins, they prepared healthy food, so they wouldn't turn to the "quick sugar fixes", they bought strollers that they could fast walk with, and they dropped the weight over a year, they were toned and had no sagging skin. Losing weight is about healthy eating, exercise and getting sleep, which granted can be difficult especially when baby has colic, I've certainly done plenty of shifts with my families children just to keep them sane, having support will help :)