Americans are having fewer children, and the latest news is that the U.S. birth rate has dipped to a 32-year low. A cross-party coalition in Washington thinks political intervention can mitigate the decline, but pump the brakes. Declining U.S. birth rates are the product of large cultural forces that the federal government can’t buy off with subsidies or income transfers.

The decline in birth rates reported by the Centers for Disease Control and Prevention isn’t all bad news. The birth rate among teens age 15-19 fell 7% last...