Kim Kardashian West is expecting again, via surrogate! News just broke that the Wests’ surrogate is pregnant with the couple’s fourth child — but years ago, Kim gave birth to her first two children, North, 5, and Saint, 3, leaving us to wonder: How does she have nary a fine line or wrinkle on her entire body?

Sure, she has the funds to afford an expensive skincare regimen, but like any makeup mogul, she has a few inexpensive ride-or-die beauty products she swears by, including Bio-Oil. The oil is formulated with plant extracts and vitamins A and E — and good news for us, only costs $20. Even better news? Right now, you can score Kim’s secret weapon for stretch marks for 20 percent off during Dermstore’s New Year Sale. All you have to do is use the promo code SILVER at checkout to snag it for $16. Unreal, right?

Buy It! Bio-Oil, $15.99 (orig. $19.99); dermstore.com

The Keeping Up With the Kardashians star has raved about Bio-Oil for years, often including it in her favorite drugstore products roundups on her website. “[Bio-Oil] just makes my skin glow, and it has so many benefits,” Kim wrote in a recent post. “If you have a scar or stretch marks, you just massage the oil onto the area two times a day.” It’s also said to improve the appearance of fine lines, wrinkles, and uneven skin tone, and helps the skin retain moisture. “When I was pregnant, I would apply it like crazy, lol,” she added. “This oil totally saved me.”

Kim isn’t the only Kardashian sister who loves this oil. In a post on her own website, Khloé shared her go-to products for stretch mark prevention during her pregnancy, including Bio-Oil.

Pick up a few of Kim’s other skincare faves (below) while they’re marked way down, before Dermstore’s huge sale ends October 12.

RELATED PHOTOS: Shop These Celeb-Loved Beauty Products During Dermstore’s Massive Sale!

Dr. Dennis Gross Peel Packettes

Buy It! Dr. Dennis Gross Alpha Beta Universal Daily Peel Packettes, $120 (orig. $150); dermstore.com

Cover FX Primer

Buy It! Cover FX Anti-Aging Primer, $30.40 (orig. $38); dermstore.com

By Terry Balm Cleanser

Buy It! By Terry Cellularose Nutri-Pure Comforting Balm Cleanser, $54.50 (orig. $68); dermstore.com