Advanced maternal age, in a broad sense, is the instance of a woman being of an older age at a stage of reproduction, although there are various definitions of specific age and stage of reproduction. The variability in definitions is in part explained by the effects of increasing age occurring as a continuum rather than as a threshold effect.

Average age of first childbirth has been increasing, especially in OECD countries, among which the highest average age is 32.6 years (South Korea) followed by 32.1 years (Ireland and Spain). In a number of European countries (Spain), the mean age of women at first childbirth has crossed the 30 year threshold. This process is not restricted to Europe. Asia, Japan and the United States are all seeing average age at first birth on the rise, and increasingly the process is spreading to countries in the developing world such as China, Turkey and Iran. In the U.S., the average age of first childbirth was 26.9 in 2018.

Advanced maternal age is associated with adverse reproductive effects such as increased risk of infertility, and that the children have chromosomal abnormalities. The corresponding paternal age effect is less pronounced.