Projections from the US Bureau of the Census show that as the large "baby boom" cohort ages in the 1980s, the percentage of births to women 35 years or older will increase by 37%, while the percentage of births to teenaged women, the small post-baby-boom cohort, will decrease by 32%. Between 1980 and 1990, for women aged 35 to 44 years, fertility rates are projected to increase modestly, whereas for teenagers aged 15 to 19 years, fertility rates are projected to decrease modestly. Assuming that half of pregnant women aged 35 years or older request prenatal chromosomal diagnosis, an estimated 1.1 million pregnant women aged 35 years or older will request this service during the 1980s, increasing substantially the demand for it. Simultaneously, demand for prenatal care for teenagers will decrease, due to the decrease in births to teenagers.
Adams MM, Oakley GP, Marks JS. Maternal Age and Births in the 1980s. JAMA. 1982;247(4):493-494. doi:10.1001/jama.1982.03320290039028