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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