Trying to pick a theme for your baby girl's first birthday party is sometimes the hardest part of party planning. Let me help you narrow it down with five of my favorite modern first birthday themes for one year old girls like "One Groovy Babe" retro theme, "First Year Down" football birthday theme, "One Prickly Pair" cactus twin birthday theme, "One Spooky Babe" Halloween birthday party and "Oh What Fun" Christmas birthday theme!