Complex sentence: The second variety was used by village midwives as it was portable, lighter and thus able to be carried from home to home as became popular in the French territory of (mostly German speaking) Alasace-Lorraine.
Split into simpler sentences: The second variety was used by village midwives as was lighter and portable so the midwife could carry it from home to home. It became popular in the French territory of (mostly German speaking) Alasace-Lorraine.