A Longitudinal Study of Changes in Thyroid Related Hormones among Pregnant Women Residing in an Iodine Deficient Urban Area

Table 4

Mean values of thyroid function tests during different trimesters of pregnancy*.

Thyroid hormone	Nonpregnant women	Pregnant women
		1st trimester	2nd trimester	3rd trimester
FT4 (pmol/L)	15.6^a ± 3.2	13.0^b ± 2.8	11.5^c ± 1.9	11.3^c,d ± 1.5
FT3 (pmol/L)	3.2^a ± 0.8	3.8^b ± 1.1	3.6^c ± 0.9	3.9^b,d ± 1.0
TSH (mIU/L)	1.4^a ± 0.6	1.2^b ± 1.1	1.7^c ± 1.1	2.3^d ± 1.3

∗Different superscript letters (a, b, c, and d) indicate that the difference in mean values of thyroid tests in a row is statistically significant at 𝑃<0.05.