Table 4.

Crude and adjusted ORs of maternal chronic conditions for adverse perinatal outcomes (n=86 885)

Outcome	The number of chronic conditions
	0	1	≥2
PTB
N (%)	2125 (4.1)	1498 (5.1)	340 (6.2)
Crude OR (95% CI)	Reference	1.26 (1.17–1.34)	1.56 (1.38–1.75)
Adjusted OR (95% CI)	Reference	1.24 (1.16–1.33)	1.50 (1.33–1.69)
VPTB
N (%)	441 (0.9)	328 (1.1)	65 (1.2)
Crude OR (95% CI)	Reference	1.32 (1.14–1.52)	1.41 (1.08–1.83)
Adjusted OR (95% CI)	Reference	1.29 (1.12–1.49)	1.34 (1.03–1.74)
LBW
N (%)	3775 (7.3)	2661 (9.0)	577 (10.6)
Crude OR (95% CI)	Reference	1.27 (1.20–1.33)	1.51 (1.37–1.65)
Adjusted OR (95% CI)	Reference	1.27 (1.20–1.34)	1.49 (1.35–1.63)
VLBW
N (%)	248 (0.5)	193 (0.7)	42 (0.8)
Crude OR (95% CI)	Reference	1.38 (1.14–1.66)	1.61 (1.16–2.24)
Adjusted OR (95% CI)	Reference	1.39 (1.15–1.67)	1.62 (1.16–2.25)
ELBW
N (%)	108 (0.2)	76 (0.3)	21 (0.4)
Crude OR (95% CI)	Reference	1.24 (0.93–1.67)	1.85 (1.16–2.96)
Adjusted OR (95% CI)	Reference	1.24 (0.92–1.67)	1.81 (1.12–2.90)
SGA*
N (%)	3685 (7.1)	2443 (8.3)	522 (9.6)
Crude OR (95% CI)	Reference	1.18 (1.12–1.25)	1.39 (1.26–1.52)
Adjusted OR (95% CI)	Reference	1.17 (1.11–1.23)	1.33 (1.20–1.46)

OR, odds ratio compared with that of infants of mothers without chronic conditions, adjusted for maternal age at delivery, parity (except for SGA analysis), maternal smoking status, maternal alcohol consumption, maternal educational background and neonatal sex (except for SGA analysis).

Adjusted ORs with statistical significance are indicated in bold font.

*The total number of participants was 86 674.

ELBW, extremely low birth weight (<1000 g); LBW, low birth weight (<2500 g); PTB, preterm birth before 37 weeks of gestation; SGA, small for gestational age; VLBW, very low birth weight (<1500 g); VPTB, preterm birth before 34 weeks of gestation.