Figure 1. Birth rates, mean age of mother at first childbirth, and the proportion of infants born in the United States to women >35 years of age since 1970. Legend. The birth rate per 1000 population declined from 18.4 in 1970 to 11.8 in 2017. The mean age of mothers at first child birth increased from 21.4 years in 1970 to 26.6 in 2016. The proportion of all infants born in the USA to mothers > 35 years increased from 4.6% in 1970 to 14.9% in 2012. Birth rates are per 1,000 population estimated as of July 1 for each year except in 1970 and 1980, which were estimated as of April 1. Reproduced with permission from Bhasin S, Kerr C, Oktay K, Racowsky C. The Implications of Reproductive Aging for the Health, Vitality and Economic Welfare of Human Societies. J Clin Endocrinol Metab. 2019 Apr 16:jc.2019-00315. doi: 10.1210/jc.2019-00315. Epub ahead of print. PMID: 30990518. The original figure was based on data derived from: Centers for Disease Control and Prevention. National Vital Statistics System: birth data. Available at: Accessed 24 June 2021.