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Table 5 The effects of iodine intake and other covariates on natural logarithm of birth weight/placental weight ratio in univariate and multivariate models

From: Estimated dietary iodine intake as a predictor of placental size: evidence from the ELSPAC study

 

Univariate models

Multivariate model

β estimate

95% CI for β estimate

p-value

β estimate

95% CI for β estimate

p-value

Iodine intake [100 μg/day]

0.015

(−0.005; 0.035)

0.136

0.024

(0.004; 0.043)

0.016

Gestational diabetes

 No

(ref)

  

(ref)

  

 Yes

0.093

(0.030; 0.156)

0.004

0.106

(0.045; 0.167)

<0.001

Pre-eclampsia

 No

(ref)

  

(ref)

  

 Yes

0.008

(−0.100; 0.116)

0.883

0.039

(−0.065; 0.143)

0.460

Gestational hypertension

 No

(ref)

  

(ref)

  

 Yes

−0.099

(−0.153; −0.045)

<0.001

−0.085

(−0.138; −0.032)

0.002

Gestational age [w]

0.042

(0.037; 0.046)

<0.001

0.041

(0.036; 0.046)

<0.001

Stillborn

 No

(ref)

  

(ref)

  

 Yes

−0.008

(−0.097; 0.081)

0.860

0.008

(−0.076; 0.092)

0.848

IVF pregnancy

 No

(ref)

  

(ref)

  

 Yes

−0.116

(−0.210; −0.023)

0.015

−0.126

(−0.216; −0.037)

0.006

Congenital malformations

 No

(ref)

  

(ref)

  

 Yes

−0.029

(−0.071; 0.013)

0.179

−0.035

(−0.075; 0.006)

0.095

Smoking

 Never

(ref)

  

(ref)

  

 Past smoker

−0.012

(−0.029; 0.005)

0.178

−0.012

(−0.029; 0.005)

0.172

 Current smoker

−0.031

(−0.060; −0.002)

0.039

−0.019

(−0.049; 0.011)

0.215

Substance abuse

 No

(ref)

  

(ref)

  

 Yes

−0.029

(−0.113; 0.056)

0.501

0.000

(−0.083; 0.083)

0.998

Alcohol

 No

(ref)

  

(ref)

  

 Yes

0.015

(−0.018; 0.048)

0.372

0.016

(−0.015; 0.046)

0.317

Nutritional supplements

 No

(ref)

  

(ref)

  

 Yes

−0.050

(−0.066; −0.034)

<0.001

−0.045

(−0.061; −0.028)

<0.001

ISCO skill level - mother

 Skill level 1

(ref)

  

(ref)

  

 Skill level 2

0.009

(−0.028; 0.047)

0.634

0.006

(−0.031; 0.042)

0.764

 Skill level 3

0.029

(−0.011; 0.070)

0.160

0.016

(−0.026; 0.058)

0.444

 Skill level 4

0.039

(0.000; 0.078)

0.047

0.019

(−0.022; 0.061)

0.364

 Skill level unassigned

0.018

(−0.111; 0.147)

0.786

0.031

(−0.093; 0.155)

0.621

ISCO skill level - father

 Skill level 1

(ref)

  

(ref)

  

 Skill level 2

0.021

(−0.034; 0.076)

0.449

0.010

(−0.043; 0.063)

0.709

 Skill level 3

0.037

(−0.023; 0.097)

0.225

0.007

(−0.052; 0.067)

0.816

 Skill level 4

0.039

(−0.016; 0.095)

0.162

−0.012

(−0.069; 0.045)

0.688

 Skill level unassigned

−0.027

(−0.088; 0.033)

0.378

−0.038

(−0.097; 0.021)

0.206

Education – mother

 Basic

(ref)

  

(ref)

  

 Secondary

0.013

(−0.005; 0.030)

0.164

−0.019

(−0.040; 0.002)

0.081

 University and higher

0.030

(0.008; 0.053)

0.009

−0.029

(−0.062; 0.004)

0.081

Education – father

 Basic

(ref)

  

(ref)

  

 Secondary

0.017

(−0.003; 0.037)

0.092

0.009

(−0.014; 0.031)

0.444

 University and higher

0.036

(0.016; 0.055)

<0.001

0.030

(0.000; 0.060)

0.047

Equalized family intake [1000 CZK/month]

0.009

(−0.001; 0.019)

0.080

0.005

(−0.006; 0.016)

0.382

Age - mother [y]

0.002

(0.000; 0.003)

0.048

0.001

(−0.001; 0.003)

0.463

Height - mother [cm]

0.003

(0.002; 0.004)

<0.001

0.001

(0.000; 0.003)

0.059

Height - father [cm]

0.002

(0.001; 0.004)

<0.001

0.001

(0.000; 0.003)

0.028

Maternal preconceptional BMI [kg/m2]

−0.001

(−0.004; 0.001)

0.238

−0.001

(−0.004; 0.001)

0.345

Ethnicity – mother

 European

(ref)

  

(ref)

  

 Others

−0.075

(−0.150; −0.001)

0.048

−0.012

(−0.098; 0.073)

0.780

Ethnicity – father

 European

(ref)

  

(ref)

  

 Others

−0.037

(−0.094; 0.020)

0.204

0.011

(−0.054; 0.075)

0.740

Sex of the child

 Girl

(ref)

  

(ref)

  

 Boy

0.016

(0.000; 0.032)

0.051

0.014

(−0.001; 0.029)

0.076