Limitation of family size can exacerbate the problems of the elderly as it makes it harder for family members to care for elderly parents.
When families typically had more children, it was more likely that elderly parents could be cared for. More children meant that it was more likely that one child could take an elderly parent or parents into his/her home. It also meant that there were more children to share the financial burden of helping elderly parents. With today's smaller families, neither of these is true anymore. This makes it more likely that elderly people will be poor and/or poorly cared for as they age.