Table 7 Association of maternal PFAAs exposure and maternal TSH by trimester (adjusted results)
From: Exposure to Perflouroalkyl acids and foetal and maternal thyroid status: a review
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) | – |