She may be seven months pregnant and mother to a toddler, but one look at the Duchess of Cambridge's flawless skin and you would never guess it. So what's the secret behind the 33-year-old's pregnancy glow? An all-natural rosehip oil, apparently. According to US Weekly, Kate has been slathering Trilogy's Rosehip Oil onto her skin while carrying the second royal baby. Scroll down for video . The Duchess of Cambridge, who is seven months pregnant with her second child, is said to be a fan of Trilogy's £16.50 rosehip oil . 'Kate is very cautious of products and treatments,' a source told the magazine. 'Baby's health comes first. 'Kate continues to use rosehip oil in her daily skincare regiment. She loves the effect is has on her skin. [Her mother] Carole [Middleton] is also a fan.' The oil's description reads: 'Rosehip oil's potent natural actives make it highly effective for a variety of skin concerns including dehydrated and ageing skin. 'Trilogy’s rosehip expertise ensures the finest quality oil with minimum 80 per cent essential fatty acids (omega 3 and 6) and fatty acid (omega 9) content. Independent clinical studies show it helps improve the appearance of scars, stretchmarks, fine lines and wrinkles.' A source told the magazine: 'Kate continues to use rosehip oil in her daily skincare regiment. She loves the effect is has on her skin. [Her mother] Carole [Middleton] is also a fan' Derived from the wild rose bushes that grow high in the Chilean Andes, where the altitude and pollutant-free environment produce the highest quality rosehips, the oil’s benefits have been known by the indigenous population for hundreds of years. Not only is it rich in vitamin C and high in omega 3 and 6 fatty acids, known to heal scar tissue, it’s also a great source of retinoic acid, which studies show reduces the appearance of wrinkles and brightens skin. As with anything that Kate is reported to be a fan of, the £16.50 oil has already sold out online at Boots.com. It has also been reported that Deborah Mitchell uses Rosehip Oil in her LIA therapy treatment that Kate loves. The Kate effect strikes again? The oil has already sold out on Boots.com . Models David Gandy, right, and Miranda Kerr have also praised the oil's skin-boosting properties . It is results like these that prompted Kate Middleton’s facialist, Deborah Mitchell, to add rosehip oil to her signature LIA therapy treatment. ‘Rosehip is perfect for all ages and skin types, including those with sensitive skin conditions like rosacea and acne. I add a drop to moisturiser to boost the results - Kate loves it because it gives skin a luminous glow,’  Deborah told the Daily Mail back in 2012. Models David Gandy and Miranda Kerr have also praised the oil. ‘I put it on at night and I wake up glowing,’ Miranda has said. The model loves it so much that she even created her own version for her Kora Organics skincare line. A spokesperson for the Duchess of Cambridge declined to comment when contacted by MailOnline. Many brands are using the wonder ingredient in their products. (L-R) KORA Organics by Miranda Kerr - Luxurious Rosehip Body Oil, £45, Pai Rosehip BioRegenerate, £22, Neal's Yard Remedies Rehydrating Rose Facial Oil, £20 .
US Weekly reports that Kate, 33, has been using the product . Oil is rich in vitamin C and high in omega 3 and 6 fatty acids . Miranda Kerr and David Gandy also love the oil .