# US Birth Rate Trends: Women Over 40 vs Teenagers

## Summary

In 2023, for the first time in US history, more babies were born to women age 40 and older (4.1% of all births) than to teenagers under 20 (4.0% of all births). This crossover reflects two converging trends since 1990:

- **Teen births plummeted 73%** (from 533,483 to 142,743)
- **Births to women 40+ surged 193%** (from 50,245 to 147,054)

## Key Statistics (1990 → 2023)

| Age Group | 1990 Births | 2023 Births | Change |
|-----------|-------------|-------------|--------|
| Under 20 | 533,483 (12.8%) | 142,743 (4.0%) | -73% |
| 20-24 | 1,093,730 (26.3%) | 616,970 (17.2%) | -44% |
| 25-29 | 1,277,108 (30.7%) | 986,567 (27.4%) | -23% |
| 30-34 | 886,063 (21.3%) | 1,098,052 (30.5%) | +24% |
| 35-39 | 317,583 (7.6%) | 604,631 (16.8%) | +90% |
| 40+ | 50,245 (1.2%) | 147,054 (4.1%) | +193% |

## Age-Specific Birth Rates (per 1,000 women)

| Age Group | 1990 | 2023 | Change |
|-----------|------|------|--------|
| 15-19 | 59.9 | 13.1 | -78% |
| 20-24 | 116.5 | 57.7 | -51% |
| 25-29 | 120.2 | 91.0 | -24% |
| 30-34 | 80.8 | 94.3 | +17% |
| 35-39 | 31.7 | 54.3 | +71% |
| 40-44 | 5.5 | 12.5 | +127% |
| 45+ | 0.2 | 1.1 | +450% |

## Interpretation

The crossover happened around 2022-2023 as two trends converged:

1. **Declining teen births**: Driven by improved access to contraception, comprehensive sex education, and changing social norms around early parenthood.

2. **Increasing older motherhood**: Driven by delayed family formation (education, careers), medical advancements in fertility treatment, and economic factors.

In 1990, women under 30 accounted for 70% of births; by 2023, they accounted for just 49%. The median age of first-time mothers rose from 27 to 30 during this period.

## Data Source

**CDC National Center for Health Statistics (NCHS)**
- Report: "Effects of Age-specific Fertility Trends on Overall Fertility Trends: United States, 1990–2023"
- Authors: Anne K. Driscoll, Ph.D., and Brady E. Hamilton, Ph.D.
- Published: March 6, 2025
- Citation: National Vital Statistics Reports; vol 74 no 3
- DOI: https://dx.doi.org/10.15620/cdc/174576
- PDF: https://www.cdc.gov/nchs/data/nvsr/nvsr74/nvsr74-3.pdf
- Raw data: https://wonder.cdc.gov/natality.html

## Files in This Directory

- `births_by_age_group.csv` - Number and percentage of births by maternal age group (1990-2023)
- `birth_rates_by_age.csv` - Age-specific birth rates per 1,000 women (1990-2023)