Trimester-Specific Reference Ranges for Thyroid Hormones in Iranian Pregnant Women

Table 1

Average trimester specific values of gestational age, urinary iodine concentration and thyroid volumes in 152 healthy pregnant women.

Variable	1st trimester	2nd trimester	3rd trimester
Gestational time (week)	12.2±3.7^∗	23.8±1.8	35.7±1.5
Urinary iodine (𝜇g/dL)	228 (169, 285)^†	166 (108, 267)	143 (85, 232)
Thyroid volume (mL)	9.05±4.1^∗	10.15±4.3	10.9±5.1

*Mean ± SD, ^†median values (inter quartile range).