Kim Kardashian West has hit back at critics after she was slammed for letting her son Saint sit in a front-forward facing baby seat.

The 'Keeping Up With The Kardashians' star was criticised for not putting her 20-month-old son Saint in a rear-facing seat but she has now defended her decision to do so.

She said in a video posted to her website: ''What people didn't know is that Saint is now the weight and height requirement to sit forward-facing. Saint actually weighs more than North, if that is believable.''

Meanwhile, Kim and her husband Kanye West - who also have four-year-old daughter North together - are set to welcome another child via surrogacy and it has been revealed the couple decided to have another child because she ''missed having a baby in the family''.

A source said recently: ''After having Saint, Kim was told she couldn't carry another baby - that it would be too dangerous - and she was okay with that. She was content with two. But even after having Saint and knowing everything, Kanye was already talking about having more kids. He would want a family of five or six if it was up to him.

''Kim was never going to let herself get pregnant again. But she thinks her kids have grown up too fast and misses having a baby in the family. Things have been good for the past few months, and she started agreeing with him [about having another child].''

And it is no surprise that the pair decided to have more kids as it was previously revealed Kanye is ''crazy'' about his children.

An insider shared: ''He loves being a part of the [Kardashian] family and to involve them in the upbringing of his kids. People forget that he has a big family ... so family has always been crucial. And he wants his kids to have that. He's crazy about his kids. They keep him grounded.''