Since the early 1980s, the number of births to women over age 35 has been increasing in most European countries. Consequently, the period of highest fertility shifted from the 20-25 to the 25-30 age range. During the baby boom after World War II in France, the annual number of births rose from 610,000 in 1938 to 870,000 by the end of the 1940s. In 1964 when the baby boom children reached reproductive age, annual births were close to 850,000. The number of births in mothers over 35 increased from 47,000 in 1980 to 70,000 in 1985. The total fertility ratio was 3 children/woman by the end of the 1940s, then it declined to 1.8 between 1964 and 1976, below the replacement level up to the present time. The proportion of the ratio attributable to women over 35 age declined during the 20th century from 25% to the current 9%. Between 1964 and 1976, all the age-specific birth rates fell. In France in 1978, unwanted births dropped from 21% to 13.5% between the periods 1963 and 1967, and 1973 and 1977, respectively. In 1976, fertility in the 25-39 and the 30-34 age ranges started to increase. The main reason for the increase in fertility beyond age 35 was the decrease in nuptiality at younger ages due to more efficient birth control. Illegitimate fertility rates also rapidly increased along with single women at all ages. In Sweden, the illegitimacy ratio is currently close to 1 out-of wedlock birth in every 2 births. The illegitimacy ratio nearly doubled between 1976 and 1985 to reach 17% in the UK and 20% in France. It is not close to 6% in Switzerland, 8.5% in the Netherlands, and 9% in West Germany. On the one hand, the increase in the number of births at maternal ages over 35 occurred because the baby boom cohorts are not 25-40 year old. New cohorts will marry later and often get divorced, while out-of-wedlock fertility continues to increase. These changes will bring about the decline in fertility before age 25 and an increase between ages 25 and 35. Late fertility after age 35 will probably increase to a much smaller extent than mid-period fertility.