Gillings School of Global Public Health, University of North Carolina, Rosenau Hall, Campus Box# 7445, Chapel Hill, NC 27599-7445, USA.
Health Serv Res. 2010 Aug;45(4):1083-104. doi: 10.1111/j.1475-6773.2010.01115.x. Epub 2010 Apr 29.
To determine the effect of the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) on birth outcomes.
The Child Development Supplement (CDS) of the Panel Study of Income Dynamics (PSID). The PSID provides extensive data on the income and well-being of a representative sample of U.S. families from 1968 to present. The CDS collects information on the children in PSID families ranging from cognitive, behavioral, and health status to their family and neighborhood environment. The first two waves of the CDS were conducted in 1997 and 2002, respectively. We use information on 3,181 children and their mothers.
We use propensity score matching with multiple imputations to examine whether WIC program influences birth outcomes: birth weight, prematurity, maternal report of the infant's health, small for gestational age, and placement in the neonatal intensive care unit. Furthermore, we use a fixed-effects model to examine the above outcomes controlling for mother-specific unobservables.
After using propensity scores to adjust for confounding factors, WIC shows no statistically significant effects for any of six outcomes. Fixed-effects models, however, reveal some effects that are statistically significant and fairly substantial in size. These involve preterm birth and birth weight.
Overall, the WIC program had moderate effects, but findings were sensitive to the estimation method used.
确定妇女、婴儿和儿童特别补充营养计划（WIC）对生育结果的影响。
收入动态小组研究（PSID）的儿童发展补充（CDS）。PSID 提供了从 1968 年至今美国代表性家庭的收入和福利的广泛数据。CDS 收集了 PSID 家庭中儿童的信息，范围从认知、行为和健康状况到他们的家庭和社区环境。CDS 的前两波分别于 1997 年和 2002 年进行。我们使用了 3181 名儿童及其母亲的信息。
我们使用倾向评分匹配和多重插补来检查 WIC 计划是否会影响生育结果：出生体重、早产、母亲报告的婴儿健康状况、小于胎龄儿和新生儿重症监护病房安置。此外，我们使用固定效应模型来控制母亲特定的不可观测因素来检查上述结果。
在使用倾向评分调整混杂因素后，WIC 对六个结果中的任何一个都没有统计学上显著的影响。然而，固定效应模型揭示了一些统计学上显著且相当大的影响，涉及早产和出生体重。
总体而言，WIC 计划的影响适中，但研究结果对所使用的估计方法敏感。
