Up until the 20th century, babies and toddlers - both boys and girls - wore dresses. Around the mid 1700's, the long christening robes, and dresses, were used during christening and baptisms. (Before that, babies were kept tightly swaddled - even for the christening ceremonies.)
Expectant mothers would create the family christening gowns before the first baby was born - created by hand with pintucks, pleats, french and swiss laces - showing detailed workmanship. The fabrics, laces and embroidery flosses were white - symbolic of new life, purity and joy. These works of art were carefully stored after babies baptism and used for each new child, carried down through generations of babies. I had the opportunity to design a christening gown for a mother whose family actually had a gown created hundreds of years ago - stored in a family vault!
Todays gowns come in all styles - mass-manufactured and sold in stores, and also handmade by seamstresses and sold individually.