She must increase her bust!

Us Weekly has learned that Teen Mom 2's Jenelle Evans is going under the knife for a breast augmentation -- news that E! News reported first on Wednesday.

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"She's wanted it for a long time," a source close to Evans tells Us about the 20-year-old's plans for a boob job. "She's been to a consultation and is bragging to everyone that she's going to get them done."

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"She just doesn't want to be as small up there anymore, I guess. Gary is kind of egging her on to do it, too," the source adds, referring to Evans' marine boyfriend Gary Head.

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Evans follows in the footsteps of Teen Mom's Farrah Abraham, who went from an A to a C cup in early 2011."I thought I lost 'boobage' from having a baby," Abraham told Us during a visit to our New York City offices in June. "It was a challenging time, [but] it's helped my confidence and [made me] feel more like a woman."

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