Table 2.
Mean birth weight in newborns of females with IJD compared with reference births from the general population by year of birth, Norway 1967-2009
| Period of birth | Group | Total n | Birth weight* (gram) mean (SD) | p-value * | Mean difference in birth weight**(gram) mean (SD) | 95 % CI | p-value** |
|---|---|---|---|---|---|---|---|
| 1967-1979 | IJD | 645 | 3404.7 (626.1) | <0.001 | −61.2 (19.7) | −99.9, −22.5 | 0.002 |
| Ref | 773563 | 3486.9 (585.3) | |||||
| 1980-1989 | IJD | 1613 | 3428.9 (634.5) | <0.001 | −43.6 (12.6) | −68.3, −18.7 | 0.001 |
| Ref | 517621 | 3512.9 (584.5) | |||||
| 1990-1999 | IJD | 2508 | 3477.2 (626.5) | <0.001 | −48.5 (10.3) | −68.7, −28.3 | <0.001 |
| Ref | 581627 | 3552.5 (600.3) | |||||
| 2000-2009 | IJD | 2736 | 3500.8 (590.0) | <0.001 | −16.8 (8.7) | −33.8, 0.1 | 0.05 |
| Ref | 564299 | 3551.0 (590.9) |
*t-test **Multiple linear regression analysis with covariates for gestational age, maternal age at delivery, gender and parity
IJD inflammatory joint diseases, Ref references, SGA small for gestational age, OR odds ratio, CI confidence interval