Table 2.

Biochemical parameters during pregnancy^a

	First trimester	Second trimester	Third trimester
n	425	389	373
Weeks (weeks)	9.5 ± 1.8	25.3 ± 1.4	36.6 ± 0.6
Urinary iodine (μg/L)
Median	170.90	123.80	105.00
25th – 75th percentiles	100.00 – 261.10	73.50 – 189.50	67.00 – 153.50
10th – 90th percentiles	68.40 – 329.70	46.00 – 250.30	49.20 – 218.80
Total range	6.30 – 491.70	5.80 – 466.70	16.20 – 505.50
n (%) <50 μg/Lb	18 (4.3)	36 (9.6)	40 (10.8)
n (%) <150 μg/Lb	159 (37.4)	168 (45.0)	232 (62.2)
n (%) >250 μg/Lb	124 (29.1)	37 (10.7)	26 (6.9)
Serum TSH (µIU/mL)
Median	1.30		1.60
25th – 75th percentiles	0.80 – 1.90		1.20 – 2.10
10th – 90th percentiles	0.50 – 2.50		0.80 – 2.98
Total range	0.40 – 16.60		0.50 – 11.60
Serum fT4 (pmol/L)
Median	18.00		15.45
25th – 75th percentiles	15.45 – 23.20		11.60 – 21.80
10th – 90th percentiles	10.60 – 28.30		10.30 – 28.30
Total range	10.30 – 42.50		10.30 – 39.90
Serum Thyroglobulin (μg/L)
Median	5.09
25th – 75th percentiles	1.97 – 7.37
10th – 90th percentiles	0.38 – 15.65
Total range	0.14 – 42.0

^aUrinary iodine levels was assessed at each trimester, except for serum thyroglobulin other biochemical parameters were assessed at the study entry (first trimester) and towards the end of third trimester

^bWorld Health Organization’s criteria for assessing iodine status on population basis: for pregnant women moderate iodine deficiency <50 μg/L insufficient intake <150 μg/L and above requirement >250 μg/L