Table 3.
Fetal and Infant Outcomes for Primiparas Aged ≤15 years (n = 37,320), 16–20 years (n = 491,474), and 21–25 years (n = 500,367, Reference Category), United States, 1990.
| Without controls | With controls | ||||
|---|---|---|---|---|---|
| Mean values | Odds ratios | ||||
| ≤15 | 16–20 | 21–25 | ≤15 vs. 21–25 | 16–20 vs. 21–25 | |
| Mean birth weight, kg | 3.12 | 3.25 | 3.33 | ||
| Low birth weight: <2.5 kg, % | 11.60 | 8.06 | 6.31 | 0.94 (0.90, 0.99) | 0.95 (0.93, 0.97) |
| Birth weight, 2.5–2.9 kg, % | 17.34 | 14.26 | 11.81 | 1.01 (0.97, 1.05) | 1.03 (1.02, 1.05) |
| Birth weight, 3.0–3.4 kg, % | 40.17 | 39.60 | 38.43 | 1.07 (1.04, 1.10) | 1.05 (1.03, 1.06) |
| Birth weight, 3.5–3.9 kg, % | 20.58 | 25.47 | 29.10 | 0.93 (0.90, 0.96) | 0.98 (0.97, 1.00) |
| Birth weight, 4.0 + kg, % | 4.32 | 7.17 | 9.64 | 0.71 (0.66, 0.76) | 0.91 (0.89, 0.93) |
| Male, % | 51.75 a | 51.42 a | 51.30 a | 1.02 (1.00, 1.05) | 1.01 (1.00, 1.02) |
| Preterm birth, % | 20.24 | 12.09 | 9.06 | 1.34 (1.29, 1.39) | 1.04 (1.02, 1.05) |
| With birth weight <2.5 kg, % | 7.65 | 4.71 | 3.80 | 1.05 (0.99, 1.11) | 0.92 (0.90, 0.95) |
| With birth weight ≥2.5 kg, % | 12.45 | 7.33 | 5.32 | 1.48 (1.42, 1.55) | 1.12 (1.10, 1.15) |
| Small for gestational age, % | 13.11 | 12.41 | 10.15 | 0.87 (0.83, 0.91) | 1.00 (0.99, 1.02) |
| Apgar, 5 min, <7% | 11.78 | 10.37 | 9.73 | 0.88 (0.84, 0.92) | 0.93 (0.91, 0.94) |
| Congenital anomaly, % | 1.95 | 1.85 | 1.75 | 1.07 (0.98, 1.17) | 1.02 (0.98, 1.06) |
| Newborn abnormality, % b | 7.82 | 7.04 | 6.72 | 1.01 (0.96, 1.06) | 0.98 (0.96, 1.00) |
| Total infant mortality | 17.10 | 10.23 | 7.45 | 1.04 (0.93, 1.17) | 0.97 (0.91. 1.02) |
| Neonatal mortality | 11.25 | 6.42 | 5.22 | 0.90 (0.78, 1.04) | 0.84 (0.78, 0.90) |
| Postneonatal mortality | 5.85 | 3.81 | 2.23 | 1.45 (1.19, 1.77) | 1.29 (1.17, 1.43) |
| Sudden infant death | 2.42 | 1.58 | 0.71 | 1.65 (1.19, 2.29) | 1.63 (1.38, 1.93) |
| Fetal mortality (>20 weeks) | 15.92 | 10.47 | 9.13 | 0.80 (0.67, 0.95) | 0.79 (0.73, 0.86) |
| Infant and fetal mortality | 32.74 | 20.59 | 16.51 | 0.95 (0.86, 1.04) | 0.90 (0.86, 0.95) |
| Optimal infant outcome, % | 74.13 | 83.30 | 87.29 | 0.82 (0.80, 0.85) | 0.98 (0.96, 0.99) |
Raw means are tested for age-related differences without controls. Odds ratios with 95% confidence intervals are established via logistic regression in 1.126 million primigravidas (including all age groups), controlling tobacco use, education, marital status, prenatal visits, diabetes, and race/ethnicity. Significantly better outcomes for 16–20 years or 21–25 years are shown in bold. Mortality rates are per 1,000 births.
All are significantly different, p < .001, except where indicated by the same superscript “a.”
Abnormal conditions of the newborn include meconium aspiration, hyaline membrane disease, seizures, anemia, and the need for assisted breathing.