Table 4.

Categorical analysis of associations [β (95% CI)] of proximity to methyl bromide use within a 5-km radius during pregnancy with fetal growth parameters and length of gestation, CHAMACOS study, Salinas Valley, CA, 1999–2000 (n = 442).

Group	Range of use (kg)	n	Birth weight (g)a	p-Value	Length (cm)a	p-Value	Head circumference (cm)a	p-Value	Gestational age (weeks)b	p-Value
Trimester 1
None	<1	73	Reference		Reference		Reference		Reference
Moderatec	1–14,690	121	–13.8 (–141.1, 113.6)	0.83	–0.16 (–0.85, 0.54)	0.66	–0.25 (–0.64, 0.15)	0.21	0.70 (0.21, 1.18)	0.01
Highd	14,690–148,137	144	–27.7 (–149.9, 94.5)	0.66	–0.09 (–0.76, 0.58)	0.80	–0.06 (–0.44, 0.32)	0.75	0.59 (0.12, 1.06)	0.01
Trimester 2
None	<1	104	Reference		Reference		Reference		Reference
Moderate	1–14,690	152	–93.1 (–198.0, 11.7)	0.08	–0.62 (–1.20, –0.03)	0.04	–0.42 (–0.76, –0.08)	0.02	–0.03 (–0.47, 0.41)	0.89
High	14,690–76,306	152	–113.1 (–218.1, –8.1)	0.04	–0.85 (–1.44, –0.27)	<0.01	–0.33 (–0.67, 0.01)	0.06	–0.06 (–0.51, 0.38)	0.78
Trimester 3
None	<1	99	Reference		Reference		Reference		Reference
Moderate	1–14,690	155	14.0 (–93.1 121.1)	0.80	–0.04 (–0.64, 0.56)	0.90	–0.27 (–0.62, 0.07)	0.12	0.22 (–0.23, 0.68)	0.33
High	14,690–77,079	136	–23.0 (–133.2, 87.2)	0.68	0.02 (–0.60, 0.64)	0.95	–0.26 (–0.62, 0.09)	0.15	0.18 (–0.29, 0.64)	0.46
aAdjusted for maternal age, parity, prepregnancy BMI, poverty, country of birth, week of initiating prenatal care, gestational age, and gestational age squared.bAdjusted for maternal age, parity, prepregnancy BMI, poverty, country of birth, and week of initiating prenatal care.cModerate use is defined as less than the median (14,690kg) among participants with any methyl bromide exposure.dHigh use is defined as greater than the median (14,690kg) among participants with any methyl bromide exposure.