Treatment effects of maternal micronutrient supplementation vary by percentiles of the birth weight distribution in rural Nepal
Treatment effects of maternal micronutrient supplementation vary by percentiles of the birth weight distribution in rural Nepal
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DOI：
10.1093/jn/136.5.1389
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发表时间：
2006-05-01
影响因子：
4.2
通讯作者：
Zeger, SL
中科院分区：
文献类型：
--
作者：
Katz, J;Christian, P;Zeger, SL
在尼泊尔农村，某些产前微量营养素补充剂使出生体重增加了40-70克。通过计算对照组和给药组之间出生体重的平均差异来估计效应，该方法假设整个出生体重分布中的给药效应恒定。通过估计治疗组和对照组之间的出生体重差异（和CI）作为出生体重分布的非线性平滑函数，我们可以检查治疗组的出生体重分布形状是否与对照组不同。补充组分别补充叶酸、叶酸与铁、叶酸与铁和锌，以及多种微量营养素补充剂均补充维生素A，与对照组仅补充维生素A进行比较。复合微量营养素组的出生体重分布形状与对照组相同，但分布位置发生了变化。与对照组相比，叶酸和铁组在其分布的下尾有较少的婴儿，但在上尾有相似的比例。影响宫内生长的生物途径可能因微量营养素而异，其中一些可能对最脆弱的婴儿有益，而另一些可能对整个出生体重分布产生更恒定的影响。未来的分析方法，估计母亲补充剂对出生体重的好处，应检查是否有一个恒定的或可变的治疗效果，整个出生体重的分布。
Certain antenatal micronutrient supplements increased birth weight by 40-70 g in rural Nepal. The effect was estimated by calculating the mean difference in birth weight between control and treatment groups, which assumes a constant treatment effect across the birth weight distribution. By estimating differences (and Cl) in birth weight between treatment and control groups as a nonlinear, smooth function of the percentiles of the birth weight distribution, we can examine whether the shape of the birth weight distribution for a treatment group is different from that of the control group. Supplementation groups were folic acid, folic acid and iron, folic acid and iron and zinc, and a multiple micronutrient supplement all with vitamin A, compared with the control group of vitamin A alone. The shape of the birth weight distribution in the multiple micronutrient group was the same as that of the control group; however, the location of the distribution had shifted. The folic acid and iron group had fewer infants in the lower tail of its distribution but a similar proportion in the upper tail compared with the control group. The biologic pathways affecting intrauterine growth may vary by micronutrients such that some may confer a benefit among the most vulnerable infants, whereas others may have a more constant effect across the birth weight distribution. Future analytic approaches to estimating benefits of maternal supplementation on birth weight should examine whether there is a constant or variable treatment effect across the distribution of birth weight.