What website was that?
Websites say lots of things. That doesn’t mean they are accurate.
The fact is that the Church teaches we must have serious reasons. The Church does not define serious reasons, as it expects each couple to discern this in prayer.
So, any website that says X or Y is or is not a serious reason is giving an OPINION, not a CHURCH TEACHING.
You will find people out there posting and blogging online that think everything is a serious reason and others who think nothing is a serious enough reason, and people in between.
It is for you and your spouse to discern through reading Church documents such as Casti Connubii and Humanae Vitae, and forming your conscience-- the reasons must be serious and discerned through prayer, and in conformity with the moral teachings of the Church.
That is for the couple to discern through prayer and study of Church teaching, and perhaps the counsel of their pastor.
If the couple continues to focus on providing the “best” household for their child, they may never have children… the “best” is always over the horizon. Don’t get trapped into thinking babies need lots of stuff, or a grand house, or whatever. They don’t. They simply need parents that love them. There are plenty of Catholics in 3rd world countries who have babies living in a hut with a dirt floor and no indoor plumbing. Are they not giving their children the “best” household?
What is the “best” household? It is one filled with love for each other and the Lord.