Effect of perchlorate and thiocyanate exposure on thyroid function of pregnant women from South-West England: a cohort study

Table 4 Studies assessing the association between urinary perchlorate concentration and maternal thyroid status in pregnancy

Author (year)	Country	N	Gestation	Median UIC (μg/l)	Median UPC (range) (μg/l)	Association of UPC with
Author (year)	Country	N	Gestation	Median UIC (μg/l)	Median UPC (range) (μg/l)	Maternal TSH	Maternal FT4
Pearce, 2010 [6]	Italy	787^a	1st trimester	50–55	5 (0.04–168)	No	No
Pearce, 2010 [6]	Wales	854^b	1st trimester	98–117	2 (0.02–368)	No	No
Pearce, 2011 [7]	USA	134	1st trimester	144	7.8 (0.4–284)	No	No
Pearce, 2011 [7]	Argentina	107	1st trimester	130	13.5 (1.1–676)	No	No
Pearce, 2012 [8]	Greece	134	1st trimester	120	4.1 (0.2–118.5)	No	Yes (negative)^c
Charatcharoenwitthaya, 2014 [9]	Thailand	200	1st trimester	153.5	1.9 (0.1–35.5)	Yes (positive)	Yes (negative)
Horton, 2015 [10]	USA	284	1st trimester	235 (mean)^d	3.54 (mean)^d	Yes (positive)	No
Steinmaus, 2016 [11]	USA	1880	Median 7 weeks	155	6.5 (0.23–177)	Yes (positive)	TT4, FT4 (negative)
Mortensen, 2016 [12]	USA	359	3rd trimester	167	4.04 (geometric mean)	No	No
This study	England	308	3rd trimester	88	2.1 (0.3–143)	No	Yes (negative)

FT4 free T4, TSH thyroid stimulating hormone, NK not known, UIC urinary iodine concentration, UPC urinary perchlorate concentration
^aIncludes 261 women with hypothyroidism/hypothyroxinaemia (median UIC 55 μg/l) and 526 euthyroid women (median UIC 50 μg/l)
^bIncludes 374 women with hypothyroidism/hypothyroxinaemia (median UIC 98 μg/l) and 480 euthyroid women (median UIC 117 μg/l)
^cNegative association on univariate analysis but no longer associated after adjustments in multivariate analysis
^dCreatinine – adjusted (μg/g creatine)

ISSN: 1756-6614