Table 1.
Demographics of 3,580,755 singleton births and distribution of gestational age and term birth weight across 3,105 U.S. counties during 2016.
| Characteristic | N (%) | Gestational Age (weeks) Mean ± S.D. |
Term Birth Weight (grams)a Mean ± S.D. |
|---|---|---|---|
| Preterm Birth | |||
| Yes | 275,665 (7.7) | 34.1 ± 2.8 | -- |
| No | 3,305,090 (92.3) | 39.0 ± 1.1 | 3,383 ± 459 |
| Infant Sex | |||
| Female | 1,750,363 (48.9) | 38.7 ± 1.8 | 3,318 ± 446 |
| Male | 1,830,392 (51.1) | 38.6 ± 1.9 | 3,445 ± 462 |
| Maternal Age (years) | |||
| <25 | 936220 (26.1) | 38.6 ± 1.9 | 3,311 ± 446 |
| 25–29 | 1,050,606 (29.3) | 38.7 ± 1.8 | 3,387 ± 455 |
| 30–34 | 1,003,472 (28.0) | 38.7 ± 1.8 | 3,423 ± 460 |
| ≥35 | 590,457 (16.5) | 38.5 ± 1.9 | 3,419 ± 471 |
| Marital Status | |||
| Unmarried | 1,424,914 (39.8) | 38.5 ± 2.0 | 3,316 ± 458 |
| Married | 2,156,741 (60.2) | 38.7 ± 1.7 | 3,426 ± 455 |
| Maternal Race/Ethnicity | |||
| Non-Hispanic White | 1,899,029 (53.0) | 38.8 ± 1.7 | 3,441 ± 458 |
| Non-Hispanic Black | 503,702 (14.1) | 38.3 ± 2.2 | 3,236 ± 452 |
| Non-Hispanic Other | 332,343 (9.3) | 38.6 ± 1.7 | 3,303 ± 444 |
| Hispanic | 845,681 (23.6) | 38.6 ± 1.8 | 3,368 ± 445 |
| Maternal Education | |||
| Less than high school or equivalent | 491,945 (13.7) | 38.5 ± 1.9 | 3,317 ± 460 |
| High school diploma or equivalent | 903,808 (25.2) | 38.6 ± 1.9 | 3,340 ± 459 |
| Some college | 747,156 (20.9) | 38.6 ± 1.8 | 3,383 ± 461 |
| College degree or greater | 1,437,846 (40.2) | 38.8 ± 1.7 | 3,431 ± 452 |
| Maternal Smoking During Pregnancy | |||
| Yes | 260,479 (7.3) | 38.4 ± 2.1 | 3,219 ± 465 |
| No | 3,320,276 (92.7) | 38.7 ± 1.8 | 3,395 ± 456 |
| Pre-pregnancy Body Mass Index (BMI) | |||
| Underweight (<18.5 kg/m2) | 126,353 (3.5) | 38.5 ± 1.9 | 3,180 ± 428 |
| Healthy weight (≥18.5–24.9 kg/m2) | 1,590,485 (44.4) | 38.7 ± 1.8 | 3,343 ± 441 |
| Overweight (≥25.0–29.9 kg/m2) | 932,413 (26.0) | 38.7 ± 1.8 | 3,411 ± 456 |
| Obese (≥30.0 kg/m2) | 931,504 (26.0) | 38.5 ± 2.0 | 3,452 ± 481 |
| Rurality/Urbanicity | |||
| Metropolitan | 3,089,816 (86.3) | 38.7 ± 1.8 | 3,382 ± 458 |
| Non-metropolitan urbanized | 199,487 (5.6) | 38.6 ± 1.8 | 3,388 ± 465 |
| Less urbanized | 244,500 (6.8) | 38.6 ± 1.8 | 3,384 ± 465 |
| Thinly populated | 46,952 (1.3) | 38.6 ± 1.8 | 3,397 ± 465 |
| County-Level Private Well Use | |||
| 0–25% | 3,045,265 (85.0) | 38.6 ± 1.8 | 3,378 ± 457 |
| >25–50% | 426,397 (11.9) | 38.7 ± 1.8 | 3,409 ± 466 |
| >50–75% | 98,745 (2.8) | 38.7 ± 1.8 | 3,410±472 |
| >75% | 10,348 (0.3) | 38.7 ± 1.9 | 3,413 ± 470 |
a
Birth weight means and standard deviations calculated only among the 3,305,090 infants born at term