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Table 3 Correlation matrix between log-transformed fluoride concentrations in maternal urine, maternal urine adjusted for specific gravity, maternal serum, and amniotic fluid with fluoride concentrations in community water.

From: Maternal and fetal exposures to fluoride during mid-gestation among pregnant women in northern California

Fluoride concentrationsCommunity waterMaternal urineMaternal urine adjusted for specific gravityMaternal serumAmniotic fluid
Community water1.000.220.210.39**0.41**
Maternal urine0.221.000.80***0.38**0.28
Maternal urine adjusted for specific gravity0.210.80***1.000.41**0.37*
Maternal serum0.39**0.38**0.301.000.52***
Amniotic fluid0.41**0.280.37*0.52***1.00
  1. Note: The maternal urine adjusted for specific gravity correlations are based on 47 individuals. One person had a urinary specific gravity of 1, which corresponds to a specific-gravity adjusted fluoride concentration of 0. This is undefined when log-transformed and therefore cannot be included in the computation of correlations. We log-transformed the fluoride concentrations in maternal urine, maternal urine adjusted for specific gravity, maternal serum, and amniotic fluid to make the distributions approximately normal. The community water distribution was not transformed as it was not skewed. *p=0.05 **p=0.01 ***p=0.001