Preliminary report from the MLS indicated that exposure to C/O is associated with IG deceleration involving birth weight (BW), length (BL), and head circumference (HC) as gestation advances; this becomes apparent after 32 wk gestational age (GA) (Pediatr Res 1996;39:256A). We determined whether this effect of C/O on IG could be related to A or T use during pregnancy. In this multicenter study (Brown U, U of TN Memphis, U of Miami, Wayne State U), 1185 infants were classified as exposed (EXP) based on mother's C/O use and/or confirmation of C/O metabolites in meconium. In 7442, non-exposure (NON) to C/O was confirmed by negative meconium analysis. Of EXP, 89% were >32 wk, of whom 80.7% were exposed to T, 70% to A, and 58% to both (A+T) while in the NON group of similar GA, 20%, 31%, and 9.4% were exposed to T, A, and A+T, respectively. C/O exposure remained significantly associated with decreased growth in all parameters at GA >32 wk even when the effects of A, T or A+T were considered. At lower GA, BL was decreased in EXP, only in combination with A use; HC was decreased in combination with A or with both A and T. The table shows the means of BW (g), BL (cm), and HC (cm) for EXP and NON at gestational ages ≤32 wk and >32 wk and whether exposed to A, T, or A+T (*p<0.01 compared to NON by non-parametric test with corresponding GA, and T, A, or A+T exposure). We conclude that at later gestation >32 wk, the effect of C/O on IG persists even with A or T exposure. In those ≤32 wk, the effect of C/O on BL and HC becomes evident only with A exposure.

Table 1 No caption available.
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