The 33-year-old singer posed naked for the photo spread, and wore a sheer, white maxi dress in pictures with fiancé Matthew Rutler. Aguilera and Rutler are expecting their first child, and revealed in March the baby is a girl.
"As a woman, I'm proud to embrace my body through all stages of life, staying fearless and confident in surrendering to the unknowns the future has in store," she said in the interview.
Aguilera is already parent to 6-year-old son Max Liron with ex-husband Jordan Bratman. She previously appeared nude while pregnant with Max in Marie Claire magazine in 2007. Many celebrities, beginning with Demi Moore in 1991, have posed nude while pregnant, including Cindy Crawford, Britney Spears and Jessica Simpson.
Aguilera released her seventh studio album, Lotus, in 2012. She has served as a coach on reality competition series The Voice for five seasons, but will not participate in season seven. Gwen Stefani will temporarily take over while Aguilera is on maternity leave.