If you live in a poor country with no perspective, then you shouldn't have kids to my mind because there is a very high chance that they'll have a bad future and low quality of life, they'll grow up in bad conditions and won't see a joy in life. But I'd say again that this highly depends on individual conditions. I mostly mean the case when mother and father have health issues and can't work. If the family is poor but both man and woman have brain and ambitions, then why not? Poverty can be temporary if someone is smart.
In rich countries, I think that people should have kids. Sadly, too many people prefer to have fun in their 20s and 30s instead of having kids to support the nation and increase the birth rate in country. Kids are very important and in EU, countries help parents in many ways to raise kids but sadly, many prefer to go to clubs every day and then blame others when they hit 40s.

Also, in general, the higher the level of education is in the country, the lower the birthrate is and the lower the education level is, the higher the birthrate is. That's because raising a kid is a very serious responsibility.