Updated July 2, 2026
Just over half of US babies, 54.61%, are born "full term" at 39 to 40 weeks of pregnancy, and another 10.41% arrive preterm, before 37 weeks, according to CDC's National Center for Health Statistics data on 2024 births, published June 9, 2026. The rest split between early term, late term and post-term. Every figure below carries its source and the date it was checked, and the full table downloads as a CSV.
Gestational age at birth, United States, 2024
These are the official CDC categories, based on the American College of Obstetricians and Gynecologists' term-pregnancy definitions, applied to every live birth registered in the US in 2024:
| Category | Gestational age | Share of 2024 US births |
|---|---|---|
| Early preterm | Under 34 weeks | 2.72% |
| Late preterm | 34 to 36 weeks | 7.69% |
| Total preterm | Under 37 weeks | 10.41% |
| Early term | 37 to 38 weeks | 30.26% |
| Full term | 39 to 40 weeks | 54.61% |
| Late term | 41 weeks | 4.47% |
| Post-term | 42 weeks or more | 0.25% |
The total preterm figure (10.41%) held steady from 2023, while full-term deliveries declined slightly and early-term deliveries rose, continuing a shift in delivery timing that NCHS has tracked since 2014. There were 3,628,934 registered births in the US in 2024, up 1% from 2023's total.
Download the full table as a CSV: birth-timing-2026.csv.
How this compares to a calculated due date
This site's Due Date Calculator and others like it use Naegele's rule: add 280 days (40 weeks) to the first day of the last menstrual period, or 266 days to a known conception date. That single calculated date marks the estimated 40-week point, not a deadline. The CDC breakdown above shows why: 54.61% of births land in the 39-to-40-week "full term" window that brackets a due date, but a wide majority of babies are born on some other day within that two-week span, or in the early-term, late-term or preterm windows around it. The How Accurate Is a Due Date? guide walks through what that means in practice.
Term categories, defined
The early-term through post-term boundaries used above come from the American College of Obstetricians and Gynecologists' Committee Opinion No. 579, "Definition of Term Pregnancy," which replaced the older blanket "term" label (37 to 42 weeks) with four narrower bands after research linked early-term delivery to somewhat higher rates of newborn complications than full-term delivery:
| Term category | Gestational age | Source |
|---|---|---|
| Early term | 37 weeks 0 days to 38 weeks 6 days | ACOG Committee Opinion No. 579 |
| Full term | 39 weeks 0 days to 40 weeks 6 days | ACOG Committee Opinion No. 579 |
| Late term | 41 weeks 0 days to 41 weeks 6 days | ACOG Committee Opinion No. 579 |
| Post-term | 42 weeks 0 days or more | ACOG Committee Opinion No. 579 |
Worked example
Take someone whose calculator due date lands on a Tuesday in week 40. CDC's 2024 data says roughly a 55% chance their baby arrives somewhere in the 39-to-40-week full-term window that contains that date, a 30% chance of an early-term arrival at 37 or 38 weeks, about a 1 in 10 chance of a preterm birth before 37 weeks, and under a 5% chance of going to 41 weeks or beyond. None of those odds depend on the exact due date itself; they describe how gestational length is distributed across the whole US population, not any one pregnancy.
Methodology
- Gestational-age distribution and total births: CDC NCHS, National Vital Statistics Reports, Vol. 75, No. 2, "Births: Final Data for 2024," published June 9, 2026. Figures cover all live births registered in the United States in 2024.
- Term-category definitions: ACOG Committee Opinion No. 579, "Definition of Term Pregnancy" (American College of Obstetricians and Gynecologists).
- Due-date basis for comparison: this site's own calculator model, Naegele's rule (280 days from LMP, 266 days from conception), used on the Due Date Calculator and related tools.
- Rows we skipped: CDC's report breaks gestational age down further by maternal age, state and plurality; those cross-tabs aren't reproduced here because this page is scoped to the national, single-year total. See the source report for that detail.
These are population statistics, not a prediction for any individual pregnancy. Always confirm dating and any concerns about early or late delivery with your doctor or midwife.
Cite this page
PregnancyTools, "2026 U.S. Gestational Age at Birth Reference," pregnancy-tools.com/birth-timing-2026, 2026. The underlying table is available as a CSV download for reuse with attribution.