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 | |
|---|---|---|---|---|---|---|---|
| Maternal TSH | Maternal FT4 | ||||||
| Pearce, 2010 [6] | Italy | 787a | 1st trimester | 50–55 | 5 (0.04–168) | No | No |
| Wales | 854b | 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 |
| 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)