The gap between married and unmarried birth rates has narrowed
Since 1960, the rate of births to married mothers has decreased by 45 percent to 85.7 per 1,000 married women. During the same period, the rate of unwed childbirths has increased by 134 percent to 50.5 per 1,000 unmarried women.
Birth rates by mother's marital status, women age 15 to 44

Source: National Center for Health Statistics, National Vital Statistics Reports, 2011.