• The U.S., Canada and Mexico are all below the population replacement fertility rate.
• Persistently low fertility rates below the key 2.1 threshold can result in population declines.
• Data for this graphic is from the UN World Population Prospects’ 2025 estimates.

The fertility rate measures the average number of children a woman in a specific area will have over the course of her lifetime.

That 2.1 number is a key threshold. At this level, the area’s population remains self-sustaining (at current mortality rates, without migration).