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

Table 2

Distribution of lower or higher thyroid function tests in pregnant women as compared to the normal ranges of nonpregnant women.

Thyroid hormone	1st trimester; 𝑛 (%)	2nd trimester; 𝑛 (%)	3rd trimester; 𝑛 (%)
FT4 (11.0–22.0 pmol/L)*
Low value	53 (20.9)	67 (26.4)	60 (23.6)
High value	5 (2.0)	0	0
FT3 (2.5–5.8 pmol/L)
Low value	7 (2.8)	0	0
High value	18 (7.1)	13 (5.1)	22 (8.7)
TSH (0.3–4.0 mIU/L)
Low value	37 (14.6)	7 (2.8)	0
High value	5 (2.0)	6 (2.4)	14 (5.5)

∗Normal range derived as 95% confidence interval.