Two-earner families - Tradução em português

What are the main differences between European and U.S. demographics?
The significant difference between the United States and many European countries—as well as Japan, South Korea, and Taiwan—is the birth rate. Women in the U.S. average about 2.1 children, while in Europe overall, the figure is about 1.5.

Of course, throughout Europe, it's not all equal. France, where the figure is around two, is one of the exceptions to the rule. So you could compare some countries of Europe not only to the U.S., but also to France. In both of those countries, they made the adjustment many years ago—especially in the case of France—to support two-earner families, support parents with children with various types of child payments, tax credits, or provision for daycare. That has not necessarily been done so well in other countries.

Dear fellows,
I would like to know the meaning of "two-earner families" in the text.
Thank you,
clmsantos