they wont even use the new-fangled automobiles...pretty sure they arent using birth control. maybe they have mastered the rhythm method.
edit: after a little research it is apparent they get a lot less practice than the rest of us. they arent even supposed to use the rhythm method:
Amish
Not only are all types of artificial birth control forbidden in Old-Order
Amish communities, but any varieties of
natural family planning, such as
calendar-based methods, are also condemned.[SUP]
[54][/SUP] [SUP]
[53][/SUP] However, especially in recent years, more Amish women have begun using contraception. This trend is more pronounced in communities where few of the men earn their living through farming.[SUP]
[55]
[/SUP]