Table 2.

Binomial logistic regression: stepwise model building on the association between healthcare costs and perinatal outcomes, background characteristics, monthly household income and neighborhood deprivation

	Model 1		Model 2		Model 3		Model 4
	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI
Preterm birth	2,55	2,48 – 2,61	2,85	2,77 – 2,93	2,84	2,76 – 2,91	2,83	2,76 – 2,91
Small for gestational age	1,41	1,38 – 1,45	1,46	1,43 – 1,50	1,45	1,42 – 1,49	1,44	1,41 – 1,48
Maternal age			0,99	0,99–0,99	0,99	0,99 – 0,99	0,99	0,99 – 0,99
Children’s year of birth: 2012			0,92	0,90 – 0,94	0,92	0,90 – 0,94	0,92	0,90 – 0,94
Children’s year of birth: 2013			1,38	1,36 – 1,41	1,38	1,36 – 1,41	1,38	1,35 – 1,41
Children’s year of birth: 2014			7,70	7,55 – 7,85	7,69	7,54 – 7,84	7,65	7,50 – 7,81
Multiparous			0,99	0,98 – 1,02	0,98	0,96 – 0,99	0,98	0,96 – 0,99
Immigrant status			1,06	1,04 – 1,07	1,03	1,02 – 1,05	1,00	0,98 – 1,02
Monthly household income					0,99	0,99 – 0,99	0,99	0,99 – 0,99
Neighborhood deprivation							1,02	1,01 – 1,02

Model 1: AIC = 528,441

Model 2: AIC = 480,333

Model 3: AIC = 480,103

Model 4: AIC = 479,964

Healthcare cost – reference group: €0 - €1001,85

High healthcare costs: €1001,85 and higher

Bold = p-value < 0·05