Table 2.
Relative risk for adverse birth outcomes by parity, among overall women and subgroups
| Crude RR (95% CI) | Adjusted RR (95% CI) | |
|---|---|---|
| PTB | ||
| Overall | 1.14 (1.12, 1.17) | 0.91 (0.89, 0.93) |
| MPTB | 1.13 (1.11, 1.15) | 0.90 (0.88, 0.93) |
| VPTB | 1.39 (1.27, 1.53) | 1.08 (0.96, 1.22) |
| LBW | ||
| Overall | 0.89 (0.86, 0.91) | 0.74 (0.72, 0.77) |
| Preterm birth | 0.89 (0.86, 0.91) | 0.89 (0.86, 0.91) |
| Term birth | 0.72 (0.69, 0.75) | 0.65 (0.62, 0.69) |
| SGA | ||
| Overall | 0.66 (0.65, 0.68) | 0.67 (0.66, 0.69) |
| Preterm birth | 0.72 (0.68, 0.78) | 0.68 (0.62, 0.74) |
| Term birth | 0.66 (0.64, 0.67) | 0.68 (0.66, 0.69) |
MPTB was defined as gestational age between 32 and 36 weeks; VPTB was defined as gestational age between < 32 weeks; PTB was defined as gestational age < 37 weeks, LBW was defined as birth weight < 2500 g; SGA was defined as birth weight below 10th centile for specific gestational age and sex
Reference group: Nulliparity
Adjusted for maternal age and race, residence, immigrant, education, pre-pregnancy obesity, paternal age and race, sex of newborn
Abbreviations: PTB Preterm Birth, LBW Low Birth Weight, SGA Small for Gestational Age, MPTB Moderate Preterm Birth, VPTB Very Preterm Birth