Child labour regulation as environmental policy?

My cultural psychology textbook makes an interesting claim about cultural influences on birth rates: Children are economic assets in societies where their labour is expected, but in industrialized and urbanized societies, they are economic liabilities. In the latter societies, children may be protected from employment. If having a child generates expense rather than revenue, people may be less eager to procreate. This supposedly helps to explain why the latter societies have lower birth rates (in addition to the cause of women being able to control their fertilities). Could child labour regulation, if it discourages having children, be an important factor in sustainability (or resiliency)?