Table 3
The “social gradient in preterm birth”; risk of preterm birth among decile 10 women compared to decile 1 women (same year), New Zealand singleton live births 1980, 1990, and 1999
| Gestational age category | ||||
|---|---|---|---|---|
| All preterm | 20–28 wk** (n=2693) | 29–32 wk (n=12669) | 33–36 wk (n=36266) | |
| Year | OR* | OR* | OR* | OR* |
| Multivariate analysis adjusted for gender, maternal age, parity, birth year, decile, and birth year*decile, year*age, year*parity, decile*age, decile*parity. | ||||
| *Odds ratios for preterm birth among decile 10 women compared to those in decile 1 for each particular year reflects to social gradient for that year. | ||||
| **Odds ratios for the 20–28 week category did not reach statistical significance. | ||||
| 1980 | 1.67 | 1.28 | 1.66 | 1.48 |
| 1990 | 1.50 | 1.37 | 1.47 | 1.32 |
| 1999 | 1.37 | 1.46 | 1.32 | 1.19 |
