Most families are completed long before the end of the childbearing ages. In 1970 only 15 percent of the own children under 5 years old had mothers over age 34. It is estimated that women 35 to 44 have completed about 97 percent of their eventual lifetime fertility. As of 1970, they averaged 2,956 children ever born per 1,000 women (including childless single women) and 3,132 children per 1,000 women ever married. They had a "replacement index" of 143, meaning that their childbearing implied a population increase of 43 percent per generation. These women, of course, bore many of their children a decade or more before 1970, when birth rates were higher than they are today. Although they set new records for modern times, they are being followed through the childbearing ages by younger cohorts of women who have averaged fewer children than women of comparable ages in 1960.