Table 1.

Demographic characteristics of the pregnant women in each trimester.

Parameter	Trimester
	First (n = 79) (<13th week)	Second (n = 108) (13–27th week)	Third (n = 86) (≥27th week)
Age (years)	27.7 ± 6.5	28.5 ± 6.6	28.0 ± 6.5	P = 0.738
BMI (kg/m2)	25.2 ± 4.8	25.8 ± 4.9	27.8 ± 4.7	P < 0.001
Median UIC (μg/L)	135	155	140	P = 0.132
Min–Max	69–285	27–403	41–316
25th–75th	107–180	117–204	104–184
% < 150 μg/L	53%	47%	58%
TSH (mIU/L)	1.50 ± 0.92	2.03 ± 1.03	1.91 ± 0.96	*P = 0.001
TT3 (nmol/L)	2.55 ± 0.43	2.94 ± 0.49	2.96 ± 0.52	*P < 0.001
TT4 (nmol/L)	144 ± 25.3	152 ± 34.0	146 ± 29.3	P = 0.350
fT3 (pmol/L)	4.59 ± 0.64	4.37 ± 0.52	4.14 ± 0.56	*P < 0.001
fT4 (pmol/L)	15.6 ± 1.8	13.3 ± 2.1	12.5 ± 1.6	*P < 0.001
sTg (μg/L)	13.9 ± 14.9	14.5 ± 14.0	12.8 ± 8.7	P = 0.701
TV (mL)	9.1 ± 4.2	9.2 ± 3.2	9.5 ± 2.9	P = 0.213

P value <0.05 was considered statistically significant.

*P values for the comparison between first and second trimester and first and third trimester.

sTg, serum thyroglobulin; TV, thyroid volume; UIC, urinary iodine concentration.