Table 8.

Multivariate regression model to assess the relationship of chest circumference (cm) with fetal dose, restricted to individuals with data taken from medical records, or medical records and logs

	Parameter estimate (+95% CI)	2-sided P value
Fetal dose (cm/Gy)	−0.884 (−1.573, −0.103)	0.023
Trimester 1 versus trimester 3	−0.017 (−0.357, 0.289)	0.921
Trimester 2 versus trimester 3	0.017 (−0.294, 0.301)	0.912
Parity ≥1 versus parity 0	0.188 (−0.091, 0.459)	0.178
Gestation weeks (cm/week)	0.258 (0.165, 0.365)	<0.001
Baby sex female versus baby sex male	−0.360 (−0.602, −0.136)	0.005
Twin versus singleton	−1.457 (−2.943, −0.409)	0.025
Maternal age (cm/year)	0.003 (−3.133, 3.661)	0.999
Maternal height (cm/cm)	0.009 (−0.085, 3.254)	1.000
Maternal weight at 1st clinic (cm/kg)	0.056 (0.024, 0.131)	0.018
Model with separate dose × trimester
Dose in trimester 1 (cm/Gy)	−10.627 (−29.577, 39.067)	0.291
Dose in trimester 2 (cm/Gy)	−1.592 (−2.310, −0.345)	0.006
Dose in trimester 3 (or missing) (cm/Gy)	−0.004 (−0.883, 1.212)	0.994
Linear quadratic model in dose
Linear dose (cm/Gy)	0.337 (−1.294, 1.944)	0.679
Quadratic dose (cm/Gy2)	−1.205 (−2.621, 0.234)	0.095

All regressions evaluated using 4999 bootstrap resamples. Model adjusted for trimester of exposure, parity, gestation weeks, baby’s sex, singleton/twin birth, maternal age at delivery of offspring, maternal height and maternal weight at first clinic visit. The estimates for the constant term and for indicators of covariate missingness are not given. Analysis of n = 882 persons with non-missing data on chest circumference and fetal dose, with data taken from medical records and/or logs