You can, BUT you need to think what sort of things you will be doing once bubs is born. Do you do any running, exercise or walking? If those are things that you do a lot (and not everyone does ) then you may find you need one as there are just some things you can't do with bubs in a sling/carrier. That said I have a hotsling and I love it to death and wish I had one for all 4 of my babies - I use it for shopping and everything. But for you on pubic transport then it would be ideal even beyond 6mths because I imagine it would be quite horrendous trying to get even the smallest stroller onto a crowed bus or train.