April 20, 2013 - 16:22 BST hellomagazine.com Tatiana Santo Domingo has returned to work at Muzungu Sisters a month after giving birth to baby Sacha, whose father is Andrea Casiraghi Tatiana Santo Domingo has returned to work a month after the birth of her son, Sacha. A photo of new-mum Tatiana was posted on Instgram by the ethical clothing company, Muzungu Sisters, she co-owns with Dana Alikhani. "Happy Friday from #muzungusisters," wrote the women from their London showroom. "Make it a good one #happyfriday #officelife #TGIF #noemailuntilmonday" In the image Tatiana, who is engaged to Monegasque royal Andrea Casiraghi, is wearing Muzungu Sisters' Aicha jacket accesorised with a bag from the company's collaboration with French designer Delphine Delafon. Dana is seen sporting the label's Sergeant Pepper jacket and colourful Jaipur beads. Fashionista Tatiana, 29, welcomed baby Sacha on 21 March at London's Portland Hospital. "Her Serene Highness Princess Caroline has the pleasure of announcing the birth of her grandson," read the official statement confirming the happy news. "Both mother and baby are doing well," the missive added. The birth prompted Andrea's blue-blooded family to fly from Monaco, eager to meet the newest addition to the Grimaldi family.Sacha is Tatiana and Andrea's first child. The couple, who have been together for eight years, are soon expected to announce their wedding date.