If by problem you mean some variant of: humans are going to stop having babies and go extinct, then yes, i agree that is rediculous. However i disagree with th

If by problem you mean some variant of: humans are going to stop having babies and go extinct, then yes, i agree that is rediculous. However i disagree with the mechanism you propose. Having less children can be evolutionarily advantous in some circumtances. People will have less children when it makes sense, and have more children when conditions change and that make sense.