Table 1.

Relationship between covariates and maternal C-reactive protein levels (≥/< median) in control subjects.

Covariates	CRP		CRP			p-value
	≥ median		< median
	Mean	SD	Mean	SD	t
Maternal age (years)	28.83	4.87	28.76	5.07	−0.12	0.91
Gestational week of blood draw	11.57	3.55	9.91	3.48	−4.54	< 0.0001
	N	%	N	%	χ2
Previous birthsa					12.48	0.0004
0	57	30.6	89	48.6
≥ 1	129	69.3	94	51.4
Parental BPD historyb					4.96	0.02
No	184	97.3	185	100
Yes	5	2.7	0	0
Parental psychiatric historyc					0.32	0.57
No	155	81.6	149	79.3
Yes	35	18.4	39	20.7
Maternal smoking during pregnancyd					0.002	0.96
No	153	85	151	84.8
Yes	27	15	27	15.2
Maternal education level					7.83	0.02
University degree	8	4.2	18	9.6
High school graduate	131	68.9	137	72.9
Less than high school	51	26.8	33	17.5
Province of birth					0.36	0.95
Southern Finland	68	35.8	66	35.1
Eastern Finland	24	12.6	21	11.2
Western Finland	68	35.8	68	36.2
Northern Finland	30	15.8	33	17.5

^aData missing for 9 controls

^bData missing for 4 controls. Diagnoses defined according to the following ICD codes: ICD-10: F31.x; ICD-9: 2962A-G, 2963A-G, 2964A-G, 2967A; ICD-8: 296.10, 296.30.

^cDiagnoses defined according to the following ICD codes: ICD-10: F10-99, excluding F31.x, F70-79; ICD-9: 291-316, excluding 2962A-G, 2963A-G, 2964A-G, 2967A, 293-294; ICD-8: 291–308, excluding 296.10, 296.30, 292–294 except for 294.30

^dData missing for 20 controls; CRP: C- reactive protein; SD: standard deviation; t: t-test value; χ²: Pearson’s chi squared test value.