Kim Kardashian West is ''on a mission'' to have another baby.

The 34-year-old reality TV star has 20-month-old daughter North with husband Kanye West and in her bid to get pregnant for a second time, has been consulting a fertility doctor.

She explained: ''I am so on a mission to get pregnant. I remember growing up being so close with my sisters, so I want siblings for North. Because it's been so tough I'm seeing a fertility doctor to see, like, exactly when I'm ovulating and really increase my odds of getting pregnant naturally.''

Kim said that she and her 37-year-old husband having been having sex as often as possible as she tries to have another baby.

She told her sister Khloe Kardashian on the premiere of the new series of 'Keeping Up with the Kardashians': ''I've been having sex 500 times a day.''

In the same episode of the TV show, Kim - who had sex with Kanye in a bathroom before a photo shoot - said: ''I was like, I'm ovulating today! So I made him come to my photo shoot.

''There's only a 20 percent chance of getting pregnant every month, I know that I'm ovulating right now, so you gotta get it in when you can get it in!''