U.S. Births to Mothers 40 and Over

## What this measures

The number of babies born in the United States in a year to mothers aged 40 and over, counted from birth certificates. Annual, final data, from 1995. The group joins WONDER's 40-to-44, 45-to-49 and 50-and-over groups.

## Why it matters

The age at which people have children has been rising for decades, and the counts by age show where that shift happens: fewer births at the youngest ages, more in the thirties and after forty. It matters for maternity care, child care, labor-force participation and how many children families end up having.

## How to read it

Births per year. The six age groups add up to all births (demography.cdc.births.total). For the mix rather than the number, read the share (demography.cdc.births_share.mother_age.40_plus).

## What it does not say

Births are counted where they occur in the United States, to residents and non-residents alike, by the year of birth. Final data only: the newest year appears about nine months after it ends. A mother's age is as recorded on the birth certificate; where it is missing NCHS imputes it. Counts say nothing about why births moved: the number of women in each age group changes with past births and migration, so a falling count can reflect fewer women of that age as much as different choices.

## Source

CDC WONDER Natality databases (wonder.cdc.gov): 1995-2002, 2003-2006 and 2007 to the latest final year, from the National Vital Statistics System birth certificates compiled by the National Center for Health Statistics (NCHS). Read through the WONDER API, national figures only. Public domain; use does not imply CDC endorsement. WONDER's data-use restrictions apply: health statistical reporting and analysis only, and no count of 9 or fewer is published. Palanor checks monthly; NCHS adds a final year once a year.