Kylie Jenner. Picture: YouTube Screenshot

Kylie Jenner kept her pregnancy a secret so she could "enjoy the whole experience" without worrying about outside pressure.

The 21-year-old reality star never confirmed her pregnancy during the nine months she was carrying her now six-month-old daughter Stormi - whom she has with her boyfriend Travis Scott - and has now revealed her decision to stay out of the limelight whilst she was pregnant came as she felt it would be "better" for her health if she kept the news to herself.

During an interview for Vogue Australia, her 22-year-old sister Kendall Jenner asked her: "One of my favourite things you did during your pregnancy ... was that you stayed really low-key during your pregnancy. I think that it was kind of beautiful ... What were you thinking when you did that and what was your whole process behind that?"

To which the 'Life of Kylie' star responded: "I knew that it would be better for us, if me and Stormi just stayed kind of low-key. Your hormones are going crazy and your emotions are more heightened, and I just felt like I wasn't prepared to ... I just knew that it would be better for me, and I could enjoy the whole experience if I did it privately. I just felt like it was a sacred special moment and I wasn't ready to share it with everybody. I just wanted to keep that to myself."

Kylie first told fans of Stormi's birth two days after she was welcomed into the world, when she took to Instagram to apologise for keeping them "in the dark" for so long.

The 'Keeping Up with the Kardashians' star wrote at the time: "I'm sorry for keeping you in the dark through all the assumptions. I understand you're used to me bringing you along on all my journeys. My pregnancy was one I chose not to do in front of the world. I knew for myself I needed to prepare for this role of a lifetime in the most positive, stress free and health way I knew how. There was no gotcha moment, no big paid reveal I had planned. I knew my baby would feel every stress and every emotion so I chose to do it this way for my little life and our happiness.

"Pregnancy has been the most beautiful, empowering and life changing experience I've had in my entire life and I'm actually going to miss it. I appreciate my friends and especially my family for helping me make this special moment as private as we could. My beautiful and healthy baby girl arrived February 1st and I just couldn't wait to share this blessing. I've never felt love and happiness like this I could burst. Thank you for understanding."