The phrase "makes sterile" implies the ability to render something free of fertility or capable of reproducing. Therefore, the antonyms for this phrase would be words that convey the opposite idea, which are "makes fertile," "enhances fertility," or "encourages reproduction." The terms "prolific," "fruitful," and "fecund" could also be used to demonstrate the opposite of "makes sterile." Some other antonyms for "makes sterile" are "stimulates growth," "boosts productivity," "optimizes fertility," "promotes fertility," and "improves fecundity." Ultimately, any phrase that communicates the idea of enhancing, increasing, or improving reproductive potential can serve as an antonym for "makes sterile.