perinatal outcomes: the 1982 Pelotas Birth Cohort Study, Brazil

Objective. To explore the association between maternal low birth weight (LBW) and ad-verse perinatal outcomes and to discriminate between confounders and mediating factors of these associations in a population-based birth cohort of Southern Brazil. Methods. Data from 794 female members of the 1982 Pelotas Birth Cohort Study known to have delivered a live-born singleton offspring up to December 2004 were analyzed. Maternal birth weights were recorded in 1982. The associations between maternal and offspring charac-teristics were estimated by Poisson regression. Confounding was tested for socioeconomic, de-mographic, and psychosocial factors. Maternal anthropometric characteristics and hyperten-sive diseases during pregnancy were considered mediating factors. Results. An increase of 100 grams (g) in mothers ’ birth weight predicted a gain of 21 g in their infants ’ birth weight (95 % confidence interval (CI) 13.0–29.0 g, P < 0.001). Maternal LBW was associated with offspring LBW (prevalence ratio (PR) 2.28 (95 % CI 1.34–3.89), P = 0.002), preterm birth (PR 1.78 (95 % CI 1.12–2.81), P = 0.01), and small for gestational age (SGA) (PR 1.93 (95 % CI 1.14–3.26), P = 0.01). A causal chain linking maternal LBW and offspring SGA was mediated by maternal prepregnancy weight