Reproductive trends in females with inflammatory joint disease

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
1967-1979	Ref	773563	3486.9 (585.3)	<0.001	−61.2 (19.7)	−99.9, −22.5	0.002
1980-1989	IJD	1613	3428.9 (634.5)	<0.001	−43.6 (12.6)	−68.3, −18.7	0.001
1980-1989	Ref	517621	3512.9 (584.5)	<0.001	−43.6 (12.6)	−68.3, −18.7	0.001
1990-1999	IJD	2508	3477.2 (626.5)	<0.001	−48.5 (10.3)	−68.7, −28.3	<0.001
1990-1999	Ref	581627	3552.5 (600.3)	<0.001	−48.5 (10.3)	−68.7, −28.3	<0.001
2000-2009	IJD	2736	3500.8 (590.0)	<0.001	−16.8 (8.7)	−33.8, 0.1	0.05
2000-2009	Ref	564299	3551.0 (590.9)	<0.001	−16.8 (8.7)	−33.8, 0.1	0.05

*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

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