It is going to be hard to say how your delivery would be...because I have had 3 kids, and each labor and delivery was drastically different from one another.
If you are extremly obese, however, you are going to have higher risks than someone who is of a normal weight.
~If you would happen to need a c-section, it is harder for the doctor to perform the surgery on someone who is 300 pounds than it is on someone who is 200 pounds.
~If you are extremely overweight and not fit...you are going to be physically weaker and not have the endurance of someone who is more fit and physically active. (Some people have 2 hour labors...but others have marathon labors that last hours, even days...and if you are not in good physical condition, it is going to be much harder to endure.
~The more overweight you are, the more you are at risk of complications such as gestational diabetes, etc.
My advice would be for anyone who is obese and wanting to try and conceive-would be to start living a healthier lifestyle NOW, before conception. Even going from doing no exercise to a 15-20 minute walk each day, and even losing 10-20 pounds before conception will benefit your health.