Finch Brian Karl
RAND, Santa Monica, CA 90407, USA.
Health Serv Res. 2003 Dec;38(6 Pt 2):1819-41. doi: 10.1111/j.1475-6773.2003.00204.x.
To examine whether socioeconomic status (SES) gradients emerge in health outcomes as early as birth and to examine the magnitude, potential sources, and explanations of any observed SES gradients.
The National Maternal and Infant Health Survey conducted in 1988.
A multinomial logistic regression of trichotomized birth-weight categories was conducted for normal birth-weight (2,500-5,500 grams), low birth-weight (LBWT; < 2,500 grams), and heavy birth-weight (> 5,500 grams). Key variables included income, education, occupational grade, state-level income inequality, and length of participation in Women-Infants-Children (WIC) for pregnant mothers.
A socioeconomic gradient for low birth-weight was discovered for an adjusted household income measure, net of all covariates in the unrestricted models. A gross effect of maternal education was explained by maternal smoking behaviors, while no effect of occupational grade was observed, net of household income. There were no significant state-level income inequality effects (Gini coefficient) for any of the models. In addition, participation in WIC was discovered to substantially flatten income gradients for short-term participants and virtually eliminate an income gradient among long-term participants.
Although a materialist explanation for early-life SES gradients seems the most plausible (vis-à-vis psychosocial and occupational explanations), more research is needed to discover potential interventions. In addition, the notion of a monotonic gradient in which income is salutary across the full range of the distribution is challenged by these data such that income may cease to be beneficial after a given threshold. Finally, the success of WIC participation in flattening SES gradients argues for either: (a) the experimental efficacy of WIC, or (b) the biasing selection characteristics of WIC participants; either conclusion suggests that interventions or characteristics of participants deserves further study as a potential remedy for socioeconomic disparities in early-life health outcomes such as LBWT.
探讨社会经济地位（SES）梯度是否早在出生时就已在健康结果中显现，并研究任何观察到的SES梯度的大小、潜在来源及解释。
1988年进行的全国母婴健康调查。
对正常出生体重（2500 - 5500克）、低出生体重（LBWT；<2500克）和高出生体重（>5500克）这三个分类的出生体重类别进行多项逻辑回归分析。关键变量包括收入、教育程度、职业等级、州级收入不平等以及孕妇参与妇女、婴儿和儿童（WIC）项目的时长。
在不受限制模型中，扣除所有协变量后，经调整的家庭收入指标显示出低出生体重的社会经济梯度。母亲吸烟行为解释了母亲教育程度的总体影响，而扣除家庭收入后，未观察到职业等级的影响。任何模型中均未发现显著的州级收入不平等效应（基尼系数）。此外，研究发现，对于短期参与者，参与WIC项目会大幅拉平收入梯度，而对于长期参与者，实际上会消除收入梯度。
尽管对于早期生活SES梯度，物质主义解释似乎最具合理性（相对于心理社会和职业解释），但仍需要更多研究来发现潜在干预措施。此外，这些数据对收入在整个分布范围内都有益的单调梯度概念提出了挑战，即收入在达到给定阈值后可能不再有益。最后，WIC项目在拉平SES梯度方面的成功表明：（a）WIC项目的实验效果，或（b）WIC参与者的选择偏差特征；这两个结论都表明，干预措施或参与者特征作为早期生活健康结果（如低出生体重）中社会经济差异的潜在补救措施值得进一步研究。
