Is there an effect both positive or negative to the county's economy when couples have plenty children?

In the past before the current economic era, around the 15th century and the beginning of the French industrial revolution, having many children was seen as fertility and good for both the family work force and country's also. The labour force was majorly manual and those who worked at the plantations were sort after as able bodied men or women.

But at the moment, what is the viability of having many children especially as it could reduce the per capital income.