The yarn is called mommy love silk cotton, not sure if this kind of yarn is still available online, however you can use any size 3 dk yarn.
There is not option for this exact type of yark but any dk yarn will work.

This listing is for a 0-3 baby dress pattern.
Chest 14
Length 11 inches.

Included:
1 PDF File for the dress, headband and flower

Materials
dk yarn size 3
size 4.00 hook
2 small rose buds

If you have trouble understanding the pattern or if you need any help please let me know and I will gladly help you.
I hope that you will enjoy making this little baby dress :-)