Adequacy of birth weight for gestational age according to INTERGROWTH-21st curve and factors associated with the small for gestational age

Abstract Background There are few national studies despite the knowledge about the multifactorial etiology of restricted intrauterine growth. Objective To estimate the adequacy of birth weight for gestational age and investigate factors associated with the newborns small for the gestational age (NB-SGA). Method This is a cross-sectional study in public maternity hospitals in Rio de Janeiro and Niterói, RJ, in 2011 (1,771 live births). Data sources was through interviews with the mothers and medical records. The prevalence of NB-SGA, adequate (NB-AGA) and large (NB-LGA) for gestational age newborn were estimated (INTERGROWTH21st) according to maternal, gestational and newborn characteristics. Poisson regression was used (outcome SGA). Results The prevalence rates were: 9.3% SGA and 15.9% LGA. Brown skin color (prevalence rate - PR = 1.4), low scholarship (RP=1.3), prenatal inadequacy (RP = 1.3), smoking (reduction/cessation: RP = 1.7, continuity: RP = 2.4) and arterial hypertension (RP = 1.3) were associated with SGA in the univariate analysis (p<0.20) and only smoking remained in the final model (reduction/cessation: RP = 1.7 and continuity: RP = 2.3, p<0.05). Conclusion SGA prevalence showed dose-response relationship with smoking. Population-based anti-smoking strategies should be intensified for women of childbearing age, and particularly for pregnant women, promoting prenatal care smoking-cessation practices.