I had the same concerns as you when I had to take DS with me to the clinic. I actually spoke to the receptionist on the phone about it. She put my mind at ease by telling me that lots of woman come back for subsequent children and that kids in the waiting room is very common. She also said that it can be inspiring for other woman to see that the outcome they are looking for is achievable. Obviously in some cases it may not be seen that way by some individuals who may see is as having her face rubbed in someone else's good fortune, but I think that the majority of people at an IVF clinic are very aware of what a gift a child is, and don't begrudge others for being so lucky.