and behavioral characteristics to determine associations with inadequate or excessive GWG. This analysis found no significant association between smoking and drinking and GWG outside the IOM (1990) guidelines. Little et al. (1986) found no difference in GWG between infrequent (< 7.5 g/day), occasional (7.5-15 g/day), and regular (≥ 15g/day) alcohol consumers during pregnancy. In a study of determinants of GWG in poor black adolescent mothers, Stevens-Simon and McAnarney (1992) found that alcohol use was more frequent among mothers who experienced rapid GWG. Alcohol, however, is a potent teratogen, and its effects on pregnancy outcome are independent of GWG (Hanson et al., 1978; Little et al., 1986; Jacobsen et al., 1994; Bagheri et al., 1998). Thus, any impact of alcohol consumption on GWG is of little relevance compared to its teratogenic effects.

Drug use Amphetamines are anorectic drugs, and their use during pregnancy would be expected to result in low GWG. Smith et al. (2006) assessed a cohort of 1,618 pregnant women that included 84 methamphetamine users. Analysis of GWG in the methamphetamine-exposed group showed that those who used the drug in the first two trimesters but ceased use by the third trimester gained significantly more weight than either women who used throughout pregnancy or non-exposed women, suggesting the anorexic effects of methamphetamine are limited to continuous use, and there may be a rebound in weight gain if the mother stops use. Nevertheless, this study found exposure to methamphetamines increased the incidence of SGA births 3.5 times over the non-exposed group. Graham et al. (1992) conducted a prospective study with 30 women who were social users of cocaine during the first trimester of pregnancy. No significant differences were found between the drug users and non-users for GWG, delivery complications, birth weight, and other adverse outcomes. Chronic use of cocaine, however, has been shown to be associated with adverse maternal and fetal consequences (Wagner et al., 1998; Ogunyemi and Hernandez-Loera, 2004).

Unintended Pregnancy

Evidence for an effect of unintended pregnancy on GWG appears to be conflicting. Hickey et al. (1997) found that mistimed or unplanned pregnancy was associated with an increased risk for insufficient GWG among black but not among white women. In a study by Siega-Riz and Hobel (1997), planned pregnancy was associated with a marginally statistically significant decreased risk for insufficient GWG, but only among the low and normal weight subjects in a Hispanic cohort. Using data from the National Longitudinal Survey of Labor Market Experiences of Youth, Marsiglio

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