Depends on the context - does she think you or your partner are not ready? Does she think you won't hang around? Or him? Or do you think she is goading in the hope that you may make her a grandmother? Reverse psychology and all that!
You should have asked her what she meant. She could have meant a variety of things, like don't bother because of the state of the world. Perhaps she felt you are both too busy in your lifestyles, so probably shouldn't bother there. Or she could have just been being vindictive.
Depends how she said it ..... if she said it the way I think she might of said it mabey she thinks you and your partner might not be together for long ??
whilst it depends on the context and your age so many mother in laws can be so insulting and interfering. Any decision to have children should be yours and your partners not hers. If she doesnt agree her loss good luck