Taking inspiration from the alb which a priest wears over his cassock, I made this baptismal gown from 100% snow white linen fabric, decorated with intricate lace and a gold embroidered cross on the bodice. 
Taken from a 0-3 month pattern. Measurements are approximately 9” across the waist, 25” long. Not meant to be fitted. This gown will most likely be oversized on your newborn. This is to accommodate many different size babies. Features a high low skirt.
It ties in the back that can be easily undone when it is time for the priest to anoint the back with chrism oil. 
NOTE: The skirt part of the dress is slightly off-white, comparative to the bodice part. I personally only really take notice in sunlight and even then it’s hard to tell a difference. But it is not noticeable unless you seek it out. I was not able to capture it on camera.