Yeah, probably so. If she's like most women who've just had a baby, she probably doesn't feel attractive with the baby fat that remains.
My guess would be to figure out what makes her feel good about herself and reassures her you think she's still beauriful. Maybe breakfast in bed (maybe mimosas, strawberries, eggs benedict, etc), take her to a jazz brunch, a pic of her and the kids in a nice crystal frame, a spa day gift certificate. I dunno...you'll figure it out