How Much American Babies Weigh (2025)
The average newborn is about 7.2 pounds, but twins, triplets, and smoking push a large share into low birth weight.
Key findings
- The average American newborn weighed 3,248 grams in 2025, about 7.16 pounds.
- 8.4% were low birth weight (under 2,500 grams) and 1.3% very low (under 1,500 grams).
- Multiples are far lighter: single babies averaged 3,277 grams, twins 2,352, and triplets 1,646, with over half of twins born low birth weight.
- Smoking leaves a clear mark: babies of mothers who smoked in pregnancy averaged 3,006 grams versus 3,253 for those who did not, and their low-birth-weight rate was 17.2% versus 8.2%.
Birth weight is one of the strongest early predictors of a newborn's health. This measures the average weight of every U.S. baby born in 2025, the share born underweight, and how both change with multiples and with smoking. These are exact counts from the near-census of birth records.
Birth weight, 2025
Average birth weight by plurality
| Category | Average grams |
|---|---|
| Single | 3,277 g |
| Twin | 2,352 g |
| Triplet | 1,646 g |
By plurality and smoking
| Group | Avg grams | Low birth weight |
|---|---|---|
| Single | 3,277 | 6.9% |
| Twin | 2,352 | 55.5% |
| Triplet | 1,646 | 95.2% |
| Did not smoke | 3,253 | 8.2% |
| Smoked in pregnancy | 3,006 | 17.2% |
Low birth weight is under 2,500 grams. Exact counts; no sampling margins of error.
Data Sources & Methodology
The figures on this page are computed directly from the source data below. Narrative text accompanies the figures but never generates them.
CDC/NCHS Natality (Births) Public Use File
- Vintage:
- 2025
- Access:
- BigQuery
- Cadence:
- annual
A near-census of U.S. births for the year, drawn from birth certificates. Each row is one birth, carrying the age, education, race and Hispanic origin, and marital status of the mother; prenatal care, pre-pregnancy BMI, and smoking; the delivery method, attendant, birth place, and payer; and the sex, birth weight, gestational age, plurality, and Apgar score of the infant. It supports analysis of who is being born and how, by maternal characteristics.
Every U.S. birth is registered on a birth certificate, which NCHS compiles into an annual public-use micro-file. Each record describes one birth and its mother.
The file covers essentially all registered births in the data year, not a probability sample. Statistics are exact counts; there are no sampling weights and no sampling margins of error.
To protect confidentiality, the public-use file omits state and county. Analyses here are national and by maternal and infant characteristics; state-level figures require CDC WONDER or the restricted-use file.
Gestational age uses the obstetric estimate (combined gestation); birth weight is in grams; delivery method distinguishes vaginal from cesarean; some reported items (education, payer, smoking) carry reporting flags for areas that had not adopted the 2003 certificate revision.
- No state or county geography in the public-use file.
- A few items (for example payer and smoking) were not reported by every area in early revision years; reporting flags identify coverage.
- The final annual file lags roughly a year; provisional counts via CDC WONDER are more timely but less detailed.
- Birth-certificate data depend on accurate completion by hospitals and reporting areas.
How these figures were produced
- Estimate type:
- Administrative near-census (exact counts)
- Weighting:
- None (not a weighted sample)
Suggested citation
Centers for Disease Control and Prevention, National Center for Health Statistics, 2025 Natality Public Use File. Analysis by Matt George, itsmattgeorge.com. Retrieved 2026-10-24.