Young maternal age during pregnancy is linked with adverse birth outcomes. This study examined the role of maternal nutritional status in the association between maternal age and small for gestational age (SGA) delivery and birth length. We used data from a birth cohort study in Ethiopia, involving women who were 15-24 years of age and their newborns. A mediation analysis was fitted in a sample of 1,422 mother infant dyads for whom data on birth length were available, and 777 dyads for whom gestational age and birth weight was measured. We used commands, medeff for the mediation analysis and medsens for sensitivity analysis in STATA 14. Maternal nutritional status, measured by mid-upper arm circumference, mediated 21% of the association between maternal age and birth length and 14% of the association with SGA delivery. The average direct effect (ADE) of maternal age on birth length was (β = 0.45, 95% CI [0.17, 0.99]) and the average causal mediated effect (ACME) was (β = 0.12, 95% CI [0.02, 0.15]). We also found an ADE (β = 0.31, 95% CI [0.09, 0.47]) and an ACME of (β = 0.05, 95% CI [0.003, 0.205]) of maternal age on SGA delivery. The sensitivity analysis suggests an unmeasured confounder with a positive correlation of 0.15 and 0.20 between the mediator and the outcome could explain the observed ACME for birth length and SGA, respectively. We cannot make strong causal assertions as the findings suggest the mediator partly explained the total effect of maternal age on both outcomes.

中文翻译：

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孕产妇营养状况介导了孕产妇年龄和出生结果之间的关联。

怀孕期间年轻的母亲年龄与不利的出生结果有关。本研究检查了母亲营养状况在母亲年龄与小于胎龄儿 (SGA) 分娩和出生长度之间关联中的作用。我们使用了埃塞俄比亚出生队列研究的数据，涉及 15-24 岁的女性及其新生儿。中介分析适用于 1,422 对可获取出生身长数据的母婴对和 777 对对胎龄和出生体重进行测量的样本。我们在 STATA 14 中使用命令 medeff 进行中介分析，使用 medsens 进行敏感性分析。 通过中上臂围测量的孕产妇营养状况介导了孕产妇年龄与出生身长之间 21% 的关联，以及与 SGA 关联的 14%交货。母亲年龄对出生身长的平均直接影响 (ADE) 为 (β = 0.45, 95% CI [0.17, 0.99])，平均因果介导效应 (ACME) 为 (β = 0.12, 95% CI [0.02, 0.15] ]）。我们还发现 SGA 分娩时母亲年龄的 ADE (β = 0.31, 95% CI [0.09, 0.47]) 和 ACME (β = 0.05, 95% CI [0.003, 0.205])。敏感性分析表明，中介因素与结果之间存在 0.15 和 0.20 正相关的未测量混杂因素可以分别解释观察到的出生身长和 SGA 的 ACME。我们不能做出强有力的因果断言，因为调查结果表明，中介部分解释了母亲年龄对这两种结果的总体影响。31, 95% CI [0.09, 0.47]) 和 SGA 分娩母亲年龄的 ACME (β = 0.05, 95% CI [0.003, 0.205])。敏感性分析表明，中介因素与结果之间存在 0.15 和 0.20 正相关的未测量混杂因素可以分别解释观察到的出生身长和 SGA 的 ACME。我们不能做出强有力的因果断言，因为调查结果表明，中介部分解释了母亲年龄对这两种结果的总体影响。31, 95% CI [0.09, 0.47]) 和 SGA 分娩母亲年龄的 ACME (β = 0.05, 95% CI [0.003, 0.205])。敏感性分析表明，中介因素与结果之间存在 0.15 和 0.20 正相关的未测量混杂因素可以分别解释观察到的出生身长和 SGA 的 ACME。我们不能做出强有力的因果断言，因为调查结果表明，中介部分解释了母亲年龄对这两种结果的总体影响。