Both parents being on the birth certificate plus pictures of family events together is a great addition to your proof of a real relationship; just as pictures of family events together of spouses without children is also great evidence. There is no negative consequence toward spouses without children, of course.
You submit what you have. If you have a child, congrats and submit that info ...along with the other evidence. I wouldn't classify it as your biggest evidence. I think they look at the financial documents and your living location (together or apart) the most. (Taxes, medical insurance, medical and financial power of attorney, will) etc. It doesn't have to be all of them.