Table 2

Association of psychomotor scores at preschool age with infant, maternal, socioeconomic characteristics and markers of iodine status: categorical variables

	Total		Total motor scale			Objective motor scale			Subjective motor scale
	N	Per cent	Mean	SD	p Value	Mean	SD	p Value	Mean	SD	p Value
Children characteristics
Gender					<0.0001			0.0004			<0.0001
Male	158	54.60	−0.29	1.19		−0.43	1.17		0.02	1.09
Female	126	45.40	0.30	0.94		0.03	0.92		0.61	0.93
Socioeconomic characteristics and maternal characteristics
Monthly income					0.112			0.451			0.183
<€2000	33	12.67	−0.51	1.17		0.15	1.12		−0.27	1.23
≥€2000	240	87.33	−0.19	1.07		0.30	1.05		0.01	1.10
Mother education level					0.262			0.939			0.513
No/primary	10	3.28	−0.46	1.28		0.18	1.44		−0.20	1.39
Lower high school	20	7.21	−0.58	1.23		0.17	1.30		−0.33	1.38
Upper high school	44	16.39	−0.31	1.14		0.28	1.05		−0.07	1.14
University or higher	201	73.11	−0.15	1.03		0.30	1.03		0.03	1.07
Delivery					0.066			0.107			0.071
Normal	213	75.73	−0.21	1.04		0.26	1.03		−0.03	1.07
Caesarean	39	13.92	0.00	1.22		0.59	1.22		0.26	1.30
With vacuum	27	10.03	−0.63	1.24		0.06	1.10		−0.39	1.27
Parity—first child					0.010			0.004			0.116
Yes	121	43.37	−0.23	1.17		−0.44	1.13		0.17	1.08
No	158	56.63	0.13	1.08		−0.06	1.04		0.37	1.05
Smoking during pregnancy					0.405			0.118			0.234
≥10 cigarettes/day	6	2.11	−0.60	1.19		−0.39	1.58		−0.57	1.43
<10 cigarettes/day or non-smoking	278	97.89	−0.22	1.09		0.30	1.05		−0.02	1.12
Alcohol during pregnancy					0.172			0.978			0.392
Non-consumer	188	68.08	−0.28	1.11		0.29	1.10		−0.06	1.17
Still consuming	89	31.92	−0.09	1.04		0.29	1.01		0.06	1.04
Markers of iodine status
Neonatal TSH level					0.517			0.141			0.270
<5	181	64.42	−0.26	1.02		0.21	0.98		−0.09	1.03
>5	103	35.58	−0.17	1.21		0.40	1.19		0.07	1.28
Vitamins during pregnancy					0.705			0.527			0.898
Containing iodine	48	43.59	0.06	1.17		−0.07	1.04		0.25	1.19
No vitamins	57	56.41	−0.01	0.97		−0.19	0.97		0.27	0.93
Urinary iodine concentration, lg/L					0.544			0.398			0.648
<100	72	30.37	0.08	1.04		−0.13	1.01		0.36	0.98
100–149	63	24.81	−0.04	1.12		−0.16	1.13		0.16	1.06
150–294	55	22.22	0.05	1.07		−0.16	1.03		0.35	1.02
≥250	53	22.59	−0.20	1.27		−0.43	1.15		0.21	1.25
Household salt					0.097			0.181			0.135
Iodised salt	84	34.53	−0.10	1.16		−0.25	1.10		0.17	1.11
Non-iodised salt	154	61.15	0.08	1.08		−0.14	1.06		0.38	1.04
No salt	10	4.32	−0.62	0.71		−0.76	0.68		−0.18	0.91

PsychoTSH study, Belgium, 2008–2014.
Significant associations (p values <0.05) are marked in bold. p Value from Student's t-test or analysis of variance (ANOVA).
N, number of subjects; TSH, thyroid stimulating hormone.