Table 7.
Association of maternal PFAAs exposure and maternal TSH by trimester (adjusted results)
| Reference | Author Country Year |
Effect estimate | PFHxS | PFOS | PFOA | PFNA | PFDA | PFUnA | PFDoA |
|---|---|---|---|---|---|---|---|---|---|
| TH measured during 1st Trimester | |||||||||
| [38] |
Kato Japan 2016 |
Linear regression: Adjusted β (p value) | – | ↓: − 0.214 (< 0.001)* | ↑: 0.039 (0.478) | – | – | – | – |
| [39] |
Preston USA 2018 |
Difference in maternal TH levels per quartile (Q2–4 vs. Q1) of PFAAs concentrations (95% CI) |
↑: Q2: 7.66 (− 13.1, 33.4) |
↓: Q2: − 6.91 (− 25.1, 15.7) |
↑: Q2: 16.0 (− 7.08, 44.8) |
↑: Q2: 22.6 (− 2.79, 54.5) |
– | – | – |
|
↓: Q3: − 8.58 (− 26.7, 14.0) |
↓: Q3: − 5.73 (− 24.5, 17.6) |
↑: Q3: 10.1 (− 12.0, 37.7) |
↑: Q3: 12.1 (− 9.20, 38.3) |
– | – | – | |||
|
↑: Q4: 3.27 (− 16.9, 28.4) |
↓: Q4: − 5.04 (− 24.0, 18.6) |
↑: Q4: 8.35 (− 14.1, 36.6) |
↑: Q4: 6.46 (− 13.6, 31.1) |
– | – | – | |||
| [40] |
Inoue Denmark 2019 |
Relative percentage difference per IQR increase | ↑: 1.02 (0.96, 1.08) | ↑: 1.04 (0.96; 1.14) | ↑: 1.01 (0.93; 1.1) | ↑: 1.01 (0.95; 1.08) | ↑: 0.99 (0.93; 1.05) | – | – |
| TH measured during 2nd Trimester | |||||||||
| [42] |
Webster Canada 2014 |
IQR increase in maternal PFAAs concentrations: Adjusted β (95% CI) |
↑: 0.01 (− 0.05, 0.07) |
↑: 0.1 (− 0.03, 0.2) |
↑: 0.1 (− 0.05, 0.3) |
↑: 0.2 (0.01, 0.3)* |
– | – | – |
| [41] |
Wang Norway 2013 |
Linear regression: Adjusted β (95% CI) |
↑: 0.013 (− 0.043, 0.070) |
↑: 0.008 (0.001, 0.016)* |
↓: − 0.0001 (− 0.045, 0.044) |
↑: 0.165 (− 0.023, 0.353) |
↑: 0.060 (− 0.458, 0.578) |
↑: 0.080 (− 0.200, 0.360) |
– |
| TH measured during 3rd Trimester | |||||||||
| [44] |
Wang Taiwan 2014 |
Linear regression: Adjusted β (95% CI) |
↑: 0.105 (0.002, 0.207)* |
↓: − 0.005 (− 0.024, 0.013) |
↑: 0.011 (− 0.057, 0.078) |
↑: 0.033 (− 0.046, 0.112) |
↑: 0.004 (− 0.037, 0.045) |
↑: 0.011 (− 0.009, 0.030) |
↑: 0.365 (− 0.215, 0.944) |
| [46] |
Yang China 2016 |
Spearmans partial correlation analysis. p < 0.05. Maternal exposure used. |
↓: − 0.154 | ↓: − 0.261* | ↓: − 0.124 | ↓: − 0.170* | ↓: − 0.216* | ↓: − 0.202* | ↓: − 0.231* |
| [47] |
Xiao Faroe Island 2019 |
Percent change in thyroid hormone levels per doubling of PFAA concentrations (95% CI) | ↑: 7.4 (− 11.8, 30.9) | ↑: 16.4 (−7.5, 46.5) | ↑: 12.6 (−4.5, 32.8) | ↑ 20.1 (− 5.3, 52.3) | ↑: 13.9 (−9.0, 42.6) | ↓: − 0.3 (− 15.4, 17.4) | ↓: −2.5 (− 9.2, 4.7) |
| TH measured during multiple timepoints | |||||||||
| [43] |
Berg Norway 2015 |
Mixed effects model estimated mean differences in thyroid hormone concentrations over time (2nd trimester, at birth and 6 weeks postpartum). Change across exposure quartiles (Q1 reference). NS: results not stated. | ↑: Q2: 0.18 (0.06, 0.31) | ||||||
| NS |
↑: Q3: 0.26 (0.13, 0.40)* |
NS | NS | NS | NS | – | |||
|
↑: Q4: 0.35 (0.21, 0.50)* |
|||||||||
| [45] |
Reardon Canada 2019 |
Overall main effect of PFAAs on TH (all timepoints) from mixed effects models: Adjusted β (p-value) | ↑: 0.144 (0.008)* | ↑: 0.082 (0.069) | ↑: 0.007 (0.368) | ↑: 0.005 (0.810) | ↑: 0.023 (0.647) | ↓: −0.024 (0.901) | – |
TSH (thyroid stimulating hormone), ↓ decreasing, ↑ increasing, bold format and star* indicate significant results P < 0.05, NS: no result stated, −: PFAAs not examined. Q1 (1st quartile), Q2 (2nd quartile), Q3 (3rd quartile), Q4 (4th quartile), IQR (interquartile range)
PFAAs include: PFOS Perfluorooctane sulfonate, PFOA Perfluorooctanoate, PFHxS Perfluorohexane sulfonate, PFNA Perfluorononanoic acid, PFDA Perfluorodecanoic acid, PFUnA Perfluoroundecanoic acid, PFDoA Perfluorododecanoic acid