1. There is no evidence or reason to believe families with many children have better or worse mental/psychological health/copying than families with less children. Indeed, I’ve seen surveys indicating parents with more children were generally happier than parents with less children.
2. Being honest, most people who supress the number of children they have do so for ostensible financial reasons rather than mental health reasons. They will even tell themselves that if they had ten million dollars they’d have a large family since that would make them happy.