Ms Mackintosh, 32, is a mum-of-two to daughters Sienna and Aurelia whom she shares with her husband Hugo Taylor.
She told her 1.4 million followers: “Firstly let me say that my birth experience was really positive, the playlist I made when I had Sienna was playing in the background, Hugo was there and I felt totally calm and ready, but that wasn’t the case in the few weeks before.”
The British socialite, who had caught the norovirus, explained she was admitted to hospital two weeks before she was booked in for her C-section.
Doctors thought she went into labour early when she started having contractions which were caused by her throwing up.
“I was admitted to hospital two weeks before my c section was booked in as they thought I was in early labour and having contractions brought on by throwing up after I caught the norovirus,” she continued.
“Naturally I went into panic mode as I felt so unprepared and nervous, plus Sienna was poorly at home with Hand Foot & Mouth and I knew she needed her Mama!
“It was seriously bad timing, I was monitored overnight and pumped full of fluids as I got really dehydrated, but thankfully it was a false alarm so I was discharged to go home again.”
Ms Mackintosh said the “little scare” made her appreciate the last two weeks of her pregnancy during which she spent time focusing on her wellbeing and spending time with her daughter Sienna and her husband.
She went on to describe the birth of her now eight-week-old daughter Aurelia which she said was “magical”.
She added: “As a serial planner it freaked me out thinking the baby was coming early but luckily my second C-section was everything that I hoped it would be and just magical. I asked to drop the curtain and watch Aurelia be born, which was an incredible moment that I will treasure forever!”
Heaping on praise to the staff that looked after her, she said: “I can’t thank the amazing staff at @thekensingtonwing enough for their care and support, during both of my stays.”