Silva Antônio Augusto Moura da, Bettiol Heloisa, Barbieri Marco Antonio, Brito Luiz Gustavo Oliveira, Pereira Márcio Mendes, de Aragão Vânia Maria Farias, Ribeiro Valdinar Sousa
Departamento de Saúde Pública, Universidade Federal do Maranhão, São Luís, MA, Brasil.
Rev Saude Publica. 2006 Aug;40(4):648-55. doi: 10.1590/s0034-89102006000500014.
Low birth weight children are unusual among well-off families. However, in Brazil, low birth weight rate was higher in a more developed city than in a less developed one. The study objective was to find out the reasons to explain this paradox.
A study was carried out in two municipalities, Ribeirão Preto (Southeastern Brazil) and São Luís (Northeastern Brazil), which low birth weight rates were 10.7% and 7.6% respectively. Data from two birth cohorts were analyzed: 2,839 newborns in Ribeirão Preto in 1994 and 2,439 births in São Luís in 1997-1998. Multiple logistic regression analysis was performed, adjusted for confounders.
Low birth weight risk factors in São Luís were primiparity, maternal smoking and maternal age less than 18 years. In Ribeirão Preto, the associated variables were family income between one and three minimum wages, maternal age less than 18 and equal to or more than 35 years, maternal smoking and cesarean section. In a combined model including both cohorts, Ribeirão Preto presented a 45% higher risk of low birth weight than São Luís. When adjusted for maternal smoking habit, the excess risk for low birth weight in Ribeirão Preto compared to São Luís was reduced by 49%, but the confidence interval was marginally significant. Differences in cesarean section rates between both cities contributed to partially explain the paradox.
Maternal smoking was the most important risk factor for explaining the difference in low birth weight between both cities. The other factors contributed little to explain the difference in low birth weight rates.
低出生体重儿在富裕家庭中并不常见。然而，在巴西，一个较发达城市的低出生体重率高于欠发达城市。本研究的目的是找出解释这一矛盾现象的原因。
在两个城市进行了一项研究，分别是巴西东南部的里贝朗普雷图和东北部的圣路易斯，其低出生体重率分别为10.7%和7.6%。分析了两个出生队列的数据：1994年里贝朗普雷图的2839名新生儿以及1997 - 1998年圣路易斯的2439例分娩。进行了多因素logistic回归分析，并对混杂因素进行了校正。
圣路易斯的低出生体重危险因素包括初产、母亲吸烟和母亲年龄小于18岁。在里贝朗普雷图，相关变量有家庭收入在一至三个最低工资之间、母亲年龄小于18岁以及等于或大于35岁、母亲吸烟和剖宫产。在一个包含两个队列的综合模型中，里贝朗普雷图低出生体重的风险比圣路易斯高45%。当根据母亲吸烟习惯进行校正后，里贝朗普雷图与圣路易斯相比低出生体重的额外风险降低了49%，但置信区间边缘显著。两个城市剖宫产率的差异部分解释了这一矛盾现象。
母亲吸烟是解释两个城市低出生体重差异的最重要危险因素。其他因素对解释低出生体重率差异的贡献较小。
