Table 1.

Early Pregnancy Body Mass Index and Risk of Early-onset Neonatal Sepsis

		Early-onset Neonatal Sepsis
Maternal Body Mass Index,a kg/m2	No. of Infantsb	No.	Risk/1000 Live Births	Unadjusted HR (95% CI)c	Adjusted HR (95% CI)d
<18.5	44 505	58	1.30	1.08 (.83–1.40)	1.07 (.83–1.40)
18.5–24.9	1 095 338	1327	1.21	1.00	1.00
25.0–29.9	445 478	636	1.43	1.18 (1.07–1.30)	1.19 (1.08–1.32)
30.0–34.9	148 002	305	2.06	1.70 (1.50–1.93)	1.70 (1.49–1.94)
35.0–39.9	45 151	110	2.44	2.01 (1.65–2.45)	2.11 (1.73–2.58)
≥40.0	15 806	45	2.85	2.35 (1.75–3.17)	2.50 (1.86–3.38)
Missing	177 066	432	2.44
P, trende				<.0001	<.0001
Per 1 kg/m2				1.05 (1.04–1.05)	1.05 (1.04–1.06)
Per 10 kg/m2 f				1.54 (1.43–1.65)	1.56 (1.45–1.69)

Abbreviations: CI, confidence interval; HR, hazard ratio.

^aBody mass index calculated as weight in kilograms divided by height in meters squared.

^bLive-born singleton infants in Sweden 1997–2016.

^cFrom a Cox proportional hazards model with day of hospital admission for sepsis as the outcome.

^dFrom a Cox proportional hazards model with day of hospital admission for sepsis as the outcome adjusted for maternal age, country of origin, education level, cohabitation with a partner, parity, height, smoking during pregnancy, and year of delivery. Complete case analyses including 2390 cases among 1 743 107 infants.

^eWald test when a variable representing ordinal categories of the predictor was introduced into the regression model as a continuous covariate.

^fTen units is the difference in median body mass index of women with obesity (32.8 kg/m²) and without obesity (23.1 kg/m²).