Table 3.

Pearson correlations between different derivations of ${\log }_{10}\text{-transformed}$ MUF averaged across three trimesters.

Covariates	Log ${\text{MUF}}_{\text{SG}}$	p-Value	Log ${\text{MUF}}_{\mathrm{CRE}\_1}$a	p-Value
Prepregnancy BMI	0.03	0.33	$-0.10$	0.001
Maternal age at delivery	0.12	$<0.0001$	0.17	$<0.0001$
Smoking during pregnancy (yes/no)	0.05	0.03	0.02	0.61
Level of maternal educationd	0.05	0.03	0.09	0.001
Income levele	$-0.02$	0.36	$-0.03$	0.31
Water fluoride level (reported by WTP)	0.50	$<0.0001$	0.52	$<0.0001$
No. glasses of water	0.14	$<0.0001$	0.15	$<0.0001$
Estimated amount of fluoride in a $200-\mathrm{mL}$ cup of tap water multiplied by no. of glasses of water reported to be consumed per day	0.47	$<0.0001$	0.48	$<0.0001$
No. cups of black tea	0.32	$<0.0001$	0.31	$<0.0001$
Estimated amount of fluoride in a $200-\mathrm{mL}$ cup of black tea multiplied by no. of cups of tea reported to be consumed per dayb	0.18	$<0.0001$	0.16	$<0.0001$
No. cups of green tea	0.06	0.01	0.04	0.13
Time since last voidc
Trimester 1	$-0.08$	0.004	$-0.12$	$<0.0001$
Trimester 3	$-0.12$	$<0.0001$	$-0.16$	$<0.0001$
Time at voidc
Trimester 1	0.07	0.002	0.09	0.0002
Trimester 3	0.07	0.005	0.09	0.01

Note: BMI, body mass index; CRE, creatinine; MUF, maternal urinary fluoride; SD, standard deviation; SG, specific gravity; WTP, water treatment plant.

^aData not shown for ${\text{MUF}}_{\mathrm{CRE}\_2}$ because the results were identical to ${\text{MUF}}_{\mathrm{CRE}\_1}$.

^bMean fluoride concentration of tea is based on the average fluoride content in tea when made with deionized water (i.e., $2.6\mathrm{mg}/\mathrm{L}$; Waugh et al. 2016); thus the fluoride intake from one cup of tea (assuming $200\mathrm{mL}$) would be $0.52\mathrm{mg}$. We then added the amount of fluoride that would be found if tap water was used to make the tea (i.e., if water is fluoridated at $0.7\mathrm{mg}$ F/L, then an additional $0.14\mathrm{mg}$ F would be added to the tea for a total of $0.66\mathrm{mg}$ F per $200-\mathrm{mL}$ cup of tea).

^cUrine collection time variables were not collected at Trimester 2.

^dEducation categories were based on the following seven classifications: 0, $\le \text{Grade}8$; 1, some high school; 2, high school diploma; 3, some college; 4, college diploma; 5, trade school diploma; 6, undergraduate degree, 7, graduate degree.

^eIncome categories were based on the following nine classifications: 0, $\le \$\mathrm{10,000}$; 1, $10,001–20,000; 2, $20,001–30,000; 3, $30,001–40,000; 4, $40,001–50,000; 5, $50,001–60,000; 6, $60,001–70,000; 7, $70,001–80,000; 8, $80,001–100,000; 9, $\ge \$\mathrm{100,000}$.