Jack G. Partain interprets Numbers 5:11-31 as a pregnant woman is guilty of adultery, then the drink will cause an abortion, if not, then nothing will happen.
Jack G. Partain, "Numbers," in Mercer Commentary on the Old Testament, ed. Watson E. Mills and Richard F. Wilson (Macon, GA: Mercer University Press, 2003), 180
The accused wife (implied to be pregnant) is taken to a priest who will take her before the LORD, in the Holy Presence. There she will be required to drink sacred water, tinctured with dust from the sanctuary and ink from an oath. If she is innocent, nothing will happen to her; if guilty, she will suffer dropsy (?) and become infertile (or have a miscarriage).