Table 3. Risk ratios for hospitalised infection in the first year of life comparing infants born to mothers with systemic lupus erythematosus (SLE) to infants born to mothers from the general population, overall and by preterm birth.

	Infants born to mothers with SLE, no. cases/total (%)	Infants born to general population comparators, no. cases/total (%)	Unadjusted risk ratio(95% CI)	Adjusted risk ratio(95% CI)*
Hospitalised infection in the first 3 days
Overall	6/1248 (0.5)	162/34 886 (0.5)	1.04 (0.46 to 2.33)	0.97 (0.43 to 2.23)
Term birth	5/1080 (0.5)	159/33 291 (0.5)	0.97 (0.40 to 2.36)	0.91 (0.37 to 2.22)
Preterm birth (32–37 weeks)	1/136 (0.7)	3/1354 (0.2)	NE	NE
Very preterm birth (<32 weeks)	0/32 (0.0)	0/241 (0.0)	NE	NE
Hospitalised infection in the first month of life
Overall	22/1248 (1.8)	485/34 886 (1.4)	1.27 (0.83 to 1.94)	1.25 (0.81 to 1.91)
Term birth	19/1080 (1.8)	473/33 291 (1.4)	1.24 (0.79 to 1.95)	1.21 (0.77 to 1.92)
Preterm birth (32–37 weeks)	3/136 (2.2)	12/1354 (0.9)	NE	NE
Very preterm birth (<32 weeks)	0/32 (0.0)	0/241 (0.0)	NE	NE
Hospitalised infection in the first year of life
Overall	73/1248 (5.8)	1923/34 886 (5.5)	1.06 (0.85 to 1.33)	1.13 (0.90 to 1.42)
Term birth	59/1080 (5.5)	1776/33 291 (5.3)	1.02 (0.80 to 1.32)	1.10 (0.85 to 1.41)
Preterm birth (32–37 weeks)	11/136 (8.1)	110/1354 (8.1)	1.00 (0.55 to 1.80)	1.03 (0.56 to 1.88)
Very preterm birth (<32 weeks)	3/32 (9.4)	37/241 (15.4)	0.61 (0.20 to 1.87)	0.64 (0.20 to 1.97)

HospitalizedHospitalised infections are defined as International Classification of Diseases-coded visits listing infection infections are an ICD-coded visits lisiting infection as the primary diagnosis in the inpatient component of the National Patient Register.

^*Models are adjusted for maternal age at delivery (continuous), maternal first-trimester smoking (yes/no/missing), and calendar year (continuous).

NE, not estimatable due to low number of events