 Beginning in the 1970s, a surge of women began pursuing careers and foregoing getting married and having children in their early 20s.The median age at first marriage among college graduate women, which had been stable at about 22.5 years old from the 1950s to the early 1970s (for birth cohorts from the 1930s to about 1950), increased by 2.5 years between 1972 and 1979 (for birth cohorts from about 1950 to 1955).The fraction of women not having a first birth by around 40 years old increased from 20 percent for those graduating in the early 1960s, to 28 percent for those graduating in the 1970s.