Nili S. Fox's interpretation of Numbers 5:18; possibly refers to miscarriage.
Nili S. Fox, "Numbers," in The Jewish Study Bible: Tanakh Translation, ed. Adele Berlin and Marc Zvi Brettler (New York: Oxford University Press, 2004), 295
18: Water of bitterness seems to refer to the bitter taste of the water, which contains ink and dust, probably mixed with ashes fallen to the sanctuary floor from the altar. Alternatively, the "bitterness" can refer to the punishment, apparently a distended uterus, a possible miscarriage, and ultimate infertility (so medieval commentators). A third interpretation translates the Heb term "hamarim" as "instructing," derived from a different verbal root ("y-r-h"). Thereby, the waters reveal the woman's innocence or guilt.