By Alex Tanzi From Bloomberg News WASHINGTON—The number of U.S. homes with a married couple and kids fell to a record low, according to new government data, as the pandemic further delayed weddings and more adults don’t plan to have children at all. The share of the U.S.’s 130 million households headed by married parents with children under age 18 fell to 17.8 percent in 2021 from 18.6 percent last year, according to the Census Bureau. That’s down from more than 40 percent in 1970. By absolute numbers, there are just 23.1 million homes with nuclear families, the fewest since 1959, the data show. The pandemic delayed many marriages over the past two years, adding six months to a woman’s age at first marriage—the most since 1987—to now 28.6 years. In the 1950s and ‘60s, women typically married at 20.4 years of age and 22.8 years for men. Births have …