The average age of first-time mothers in the United States has climbed to 27.5, continuing a decades-long trend that’s reshaping American families. In 1970, the average first-time mother was just 21.4 years old, highlighting how dramatically the timing of parenthood has changed over the past half-century. Researchers say the shift reflects a combination of economic pressures, higher educational attainment, changing career paths, and advances in reproductive medicine.