Dear MTB readers: How do I tell my wife she has added too much weight without hurting her feelings?

From a male MTB reader
My wife had our first child 9 months ago and she has just been growing fatter and fatter by the day. She is quite emotional and I am finding it had to communicate to her that her new gained weight is distasteful. I no longer want to see her go naked. I do not want to hurt her feelings so I am asking, whats the best way to tell her?