This aspect needs a special kind of wisdom to operate, cause following the word go into the world and multiply it didn't say otherwise that you should have kids everywhere unplanned. So all of this are planned and that's why two people come together with interest and understanding and bear forth offspring, that's to say they are ready mentally, financially and otherwise.
Go multiply doesn't also mean people should start producing children without having an income or a job at hand. Go and multiply is only used for those who are prepared to go into marriage, and being prepared for marriage doesn't guarantee one must give birth to many children but only the ones that you can cater for. When it comes to child bearing, you need to be very sensitive that no one is coming to help you, which only you have the responsibility to provide for the children.