There are several synonyms for the term "lessen fertility." Some common alternatives include "reduce fertility," "diminish fertility," "decrease fertility," "lower fertility," and "dampen fertility." Other possible synonyms for this phrase might include "weaken fertility," "impair fertility," "inhibit fertility," or "curtail fertility." Depending on the context in which the term is used, one of these alternatives may provide a more precise or evocative description of the process by which fertility is diminished or reduced. Whether discussing environmental factors, lifestyle choices, or medical interventions, there are many different ways to talk about the ways in which fertility can be impacted.