Some downsides of overpopulation are:
Poverty (one of the most common downside)
More people to feed
Cities are overcrowded
The spread of disease is rampant
Starvation
Depletion of natural resources (as more people would mean the use more resources)
Solutions for these downsides are:
Better Education – when a person is educated, he/she would know the importance of only having 1 or 2 children. They’d also be more informed about Family Planning
Family Planning – The awareness of overpopulation is tackled in this solution, as people are educated about its importance to the population as a whole
Sex Education – This method, for one, will be able to inform or educate people about the consequences of being sexually active without using contraceptives