Early fertility and lifetime fertility: evidence from the National Survey of Family growth cycle II.

This paper reviews research on the association between age at first birth and lifetime fertility and explores racial differences and possible changes over time in that relationship. Average numbers of children born during 5 year age intervals and expected completed fertility were calculated for 4 5-year birth cohorts of U.S. women categorized by race and age at first birth. The study utilized data from Cycle II of the National Survey of Family Growth conducted by the National Center for Health Statistics in 1976. Early starters were found to have excess cumulative fertility which increased to a turning point age and then stabilized or decreased. 25 was the constant turning point age for white women for the 4 cohorts but more recent cohorts showed a sharper decline in excess cumulative fertility than after that age. The turning point was 39 for the oldest black cohort and 25 for the second while in the youngest cohort the level of childbearing was no higher than among women with no birth by age 20 at completion of their first post teenage 5-year interval. Teenage mothers still expect to have more children on the average than other women and if they are more likely than other women to exceed their fertility expectations the differential could be substantial.