Table 8 Association of maternal PFAAs exposure and maternal T4 and T3 by trimester (adjusted results)

  [38]

Kato

Japan

2016

Linear regression: Adjusted β

(p value)

FT4

–

↑: 0.061 (0.236)

↑: 0.004 (0.946)

–

–

–

–

  [39]

Preston

USA

2018

Difference in maternal TH levels per quartile (Q2–4 vs. Q1) of PFAA concentrations (95% CI)

FT4Ic

↓ Q2: −0.25 (− 3.55, 3.16)

↓ Q2: − 0.56

(− 3.93, 2.93)

↓ Q2: −4.68

(− 7.93,− 1.32)*

↓ Q2: − 1.94

(−5.48, 1.72)

–

–

–

↓ Q3: − 0.35

(− 3.77, 3.18)

↓ Q3: − 1.41

(− 4.80, 2.09)

↓ Q3: −2.89

(− 6.23, 0.58)

↓ Q3: − 0.53

(− 3.79, 2.85)

–

–

–

↓ Q4: − 4.19

(− 7.43, − 0.85)*

↓ Q4: − 1.51

(− 4.92, 2.02)

↓ Q4: − 6.52

(−9.86, − 3.06)*

↓ Q4: − 1.06

(− 4.27, 2.25)

–

–

–

TT4

↓ Q2: − 0.23

(− 0.61, 0.14)

↑ Q2: 0.28

(− 0.10, 0.66)

↓ Q2: − 0.12

(− 0.51, 0.27)

↑ Q2: 0.02

(− 0.39, 0.43)

–

–

–

↑ Q3: 0.10

(− 0.28, 0.49)

↑ Q3: 0.14

(− 0.25, 0.52)

↑ Q3: 0.01

(− 0.38, 0.40)

↑ Q3: 0.08

(− 0.29, 0.45)

–

–

–

↓ Q4: − 0.34

(− 0.73, 0.04)

↑ Q4: 0.31

(− 0.08, 0.70)

↑ Q4: 0.02

(− 0.39, 0.43)

↓ Q4: −0.09

(− 0.45, 0.28)

–

–

–

  [40]

Inoue

Denmark

2019

Relative percentage difference per IQR increase

FT4

↑ 1.00 (0.98, 1.01)

↑ 1.00 (0.99, 1.02)

↑ 1.01 (0.99, 1.02)

↑ 1.00 (0.99; 1.01)

↑ 1.01 (1.00; 1.02)

  [42]

Webster

Canada

2014

IQR increase in maternal PFAA concentrations: Adjusted β (95% CI)

FT4

↓:-0.02

(− 0.1, 0.07)

↑: 0.03

(− 0.2, 0.2)

↓: − 0.06

(− 0.3, 0.2)

↓: − 0.03

(− 0.2, 0.2)

–

–

–

  [44]

Wang

Taiwan

2014

Linear regression: Adjusted β (95% CI)

FT4

↓: − 0.010

(− 0.023, 0.003)

↑: 0.001

(− 0.002, 0.003)

↓: − 0.003

(− 0.012, 0.005)

↓: − 0.019

(− 0.028, − 0.009)*

↓: − 0.001

(− 0.006, 0.005)

↓: − 0.004

(− 0.007, − 0.002)*

↓: − 0.132

(− 0.204, − 0.059)*

TT4

↓:-0.130

(− 0.316, 0.057)

↑: 0.019

(− 0.016, 0.053)

↑: 0.011

(− 0.108, 0.130)

↓: − 0.189

(− 0.333, − 0.046)*

↑: 0.047

(− 0.028, 0.123)

↓: − 0.062

(− 0.097, − 0.026)*

↓: − 1.742

(− 2.785, − 0.700)*

TT3

↓:-0.002

(− 0.005, 0.001)

↑: 0.000

(− 0.002, 0.001)

↓:-0.000

(− 0.002, 0.009)

↓: − 0.001

(− 0.003, 0.002)

↑: 0.002

(0.000, 0.003)*

↓: − 0.000

(− 0.001, 0.000)

↓: − 0.005

(− 0.022, 0.011)

  [46]

Yang

China

2016

Spearmans

partial

correlation

analysis

Maternal exposure used.

FT3

↑: 0.124

↑: 0.025

↑: 0.024

↓: − 0.063

↓: − 0.087

↓: − 0.121

↓: − 0.268*

FT4

↑: 0.038

↓: − 0.057

↑: 0.000

↓: −0.072

↓: − 0.086

↓: − 0.062

↓: − 0.160*

TT3

↑: 0.084

↑: 0.008

↑: 0.102

↓: −0.018

↓: −0.079

↓: − 0.097

↓: − 0.301*

TT4

↑: 0.084

↑: 0.021

↑: 0.062

↓: −0.006

↓: −0.010

↑: 0.030

↓: − 0.160*

  [47]

Xiao

Faroe Island

2019

Percent change in thyroid hormone levels per doubling of PFAA concentrations (95% CI)

FT4I

↑: 4.4 (− 2.3, 11.6)

↓: −0.8 (− 8.2, 7.4)

↓: − 0.6 (− 6.1, 5.1)

↓: − 1.2 (− 8.9, 7.3)

↑: 0.2 (− 7.2, 8.1)

↑: 2.3 (− 3.1, 8.1)

↑: 0.2 (− 2.2, 2.6)

FT3

↓: − 0.7 (−5.6, 4.5)

↑: 2.2 (− 3.6, 8.5)

↑: 3.1 (− 1.2, 7.6)

↓: − 2.7 (− 8.5, 3.6)

↓: − 1.4 (− 6.9, 4.5)

↓: − 1.8 (− 5.8, 2.4)

↑: 0.6 (− 1.3, 2.4)

FT4

↑: 5.9 (− 0.2, 12.4)

↓: − 2.9 (− 9.4, 4.3)

↓: − 0.4 (− 5.4, 4.8)

↓: − 5.7 (− 12.4, 1.4)

↓: − 1.5 (− 8.1, 5.5)

↓: − 0.1 (− 5.0, 5.0)

↑: 0.2 (− 2.0, 2.4)

TT4

↑: 0.4 (− 6.9, 8.2)

↑: 0.1 (−8.3, 9.3)

↑: 0.7 (− 5.5, 7.3)

↓: − 1.2 (− 9.9, 8.2)

↓: − 2.1 (− 10.1, 6.7)

↑: 0.4 (− 5.6, 6.9)

↑: 0.1 (− 2.6, 2.9)

T3RU

↑: 4.0 (− 0.4, 8.5)

↓: − 0.9 (− 5.8, 4.3)

↓: − 1.3 (− 4.9, 2.3)

↑: 0.1 (− 5.1, 5.5)

↑: 2.2 (− 2.7, 7.5)

↑: 1.9 (− 1.7, 5.7)

↑: 0.1 (− 1.5, 1.7)

  [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.

TT3

NS

NS

NS

NS

↓: Q2: − 0.04

(− 0.08. 0.04)

NS

↓: Q3: −0.05

(− 0.08, 0.00)

–

↓:Q4: −0.1

(− 0.14, − 0.06)*

FT3

NS

NS

NS

NS

NS

↓ Q2: −0.08

(−0.15, − 0.00)*

↓: Q3: − 0.09

(−0.16, − 0.01)*

–

↓ Q4: −0.18

(− 0.25, − 0.12)*

TT4

NS

NS

NS

NS

NS

NS

–

FT4

NS

NS

NS

NS

NS

NS

–

  [45]

Reardon

Canada

2019

Overall main effect of PFAAs on TH (all timepoints) from mixed effects models: Adjusted β (p-value)

FT4

↓:-0.006 (0.034)*

↓:-0.000 (0.999)

↓:-0.002 (0.138)

↓:-0.004 (0.379)

↓:-0.010 (0.314)

↓:-0.037 (0.321)

–

FT3

↑:0.000 (0.955)

↑:-0.003 (0.242)

↑:0.001 (0.535)

↑:0.004 (0.330)

↑:0.003 (0.736)

↑:0.014 (0.698)

–