Measures of fertility for very young adolescents, as well as for women at very advanced maternal ages, are important for identifying the prevalence of high-risk pregnancies and for anticipating the age-specific health needs of mothers and their infants. The production and evaluation of such measures equip national statistics offices (NSOs) to better represent childbearing across the reproductive life span and build evidence of age-specific vulnerabilities. With more holistic and specific fertility data, international aid donors can formulate and refine expectations of the health needs among populations they endeavor to serve.

This brief will outline the medical, social, and societal health implications of childbearing for populations at the very young and very old stages of reproductive life. It will then describe the data, methods, and technical challenges involved in measuring early and late childbearing. Finally, it will explore current metrics available for fertility levels among these nontraditional age groups, as well as larger health and demographic contexts in the low- and middle-income countries (LMICs) where the highest rates of early and late childbearing occur.