page_title: Advanced maternal age
section_title: Risk of birth defects
hierarchical_section_title: Advanced maternal age / Effects / Risk of birth defects
caption_attribution_description: English: The risk of having a Down syndrome pregnancy in relation to a mother's age. Data from https://www.ncbi.nlm.nih.gov/pubmed/11943789
context_page_description: 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.
  In Western, Northern, and Southern Europe, first-time mothers are on average 27 to 29 years old, up from 23 to 25 years at the start of the 1970s. In a number of European countries, 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.
context_section_description: A woman's risk of having a baby with chromosomal abnormalities increases with her age. Down syndrome is the most common chromosomal birth defect, and a woman's risk of having a baby with Down syndrome is:
  At age 20, 1 in 1,441
  At age 25, 1 in 1,383
  At age 30, 1 in 959
  At age 35, 1 in 338
  At age 40, 1 in 84
  At age 45, 1 in 32
  At age 50, 1 in 44
caption: The risk of having a Down syndrome pregnancy in relation to a mother's age.
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