The second half of the 17th century was the high tide of child bearing in Europe. 20 or so children to a family was not un-common in well-to-do theologically radical families (Neo-Pla-tonist gender roles = no contraception). Child mortality remained high (40%, mostly before the age of 3) or was even higher than usual in pre-modern societies.
With industrialism, from about 1800 women no longer had a child each year, and in the second half of the century numbers dropped considerably. So did child mortality.
What did not change was the (great) proportion of unmarried to married grown-ups.
In the 20th century the number of children to a family dropped to 2 or 3 or 1,5.
Now very few died as infants and about half married as grown ups.
Today these demographic changes are at hand in other parts of the world. Today's pre-modern societies are entering the European 19th century.
As always, there are sub-cultures within the big picture, as you can read if you click on the headline.
Överfört från Thinking Anglicans (länk till höger)