Women aged 15 to 49 years have 1.3 biological children and men aged 15 to 49 years have fathered 0.9 children on average, according to a study published online Jan. 10 in the National Health Statistics Reports, a publication from the U.S. Centers for Disease Control and Prevention.

Gladys M. Martinez, Ph.D., and Kimberly Daniels, Ph.D., from the National Center for Health Statistics in Hyattsville, Maryland, present national estimates of selected fertility measures among 9,746 men and 11,695 women aged 15 to 49 years in the United States in 2015 to 2019 using data from the National Survey of Family Growth.

The researchers found that 84.3 percent of women had given birth and 76.5 percent of men had fathered a child among those aged 40 to 49 years in 2015 to 2019. On average, among those aged 15 to 49 years, women had 1.3 and men had fathered 0.9 children. The mean age at first birth was 24.1 and 27.0 years for women and men, respectively. Among women, 29.7 and 52.1 percent of first births occurred during the and during ages 20 to 29 years, respectively. Among men, 7.3 and 58.0 percent of first births occurred at ages younger than 20 years and during ages 20 to 29 years, respectively.

Nearly one-third of women aged 15 to 49 years with a birth had one birth at the time of the interview, while one-third had a second birth within 36 months of their first birth and one-third had a second birth more than 36 months after the first . Among women, about one-half of first births occurred before marriage and one-half of these occurred within cohabiting unions.

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