The announcement comes a month after she scrapped concerts in the UK and Europe, and affects 55 further concerts in the US and Canada this summer.
Speaking in a Twitter video, the 49-year-old told her fans, "My husband and I are planning our family - so I'm going to have to delay the tour. Please, if you can, try and understand that it's important that I do this now.
"I have to rest up (on) doctor's orders. I will continue the tour as soon as I possibly can."
Jackson, who returned to the top of the Billboard charts last year with her eleventh album, Unbreakable, is married to fashion tycoon Wissam Al Mana.