Brown Mary M, Kuhle Stefan, Smith Bruce, Allen Victoria M, Payne Jennifer, Woolcott Christy G
Perinatal Epidemiology Research Unit, Depts of Obstetrics & Gynaecology and Pediatrics, Dalhousie University, Halifax, NS, Canada.
Department of Mathematics and Statistics, University of New Brunswick, Saint John, NB, Canada.
Am J Epidemiol. 2025 Feb 5;194(2):389-396. doi: 10.1093/aje/kwae214.
The objectives of this study were to examine the total effect of grandmaternal (G0) prepregnancy body mass index (BMI) on infant (G2) birthweight z score and to quantify the mediation role of maternal (G1) prepregnancy BMI. Data were extracted from the Nova Scotia 3G Multigenerational Cohort. The association between G0 prepregnancy BMI and G2 birthweight z score and the mediated effect by G1 prepregnancy BMI were estimated using g-computation with adjustment for confounders identified using a directed acyclic graph and accounting for intermediate confounding. A total of 20 822 G1-G2 dyads from 18 450 G0 participants were included. Relative to G0 normal weight, G0 underweight decreased mean G2 birthweight z score (-0.11; 95% CI, -0.20 to -0.030), whereas G0 overweight and obesity increased mean G2 birthweight z score (0.091 [95% CI, 0.034-0.15] and 0.22 [95% CI, 0.11-0.33], respectively). G1 prepregnancy BMI partly mediated the association, with the largest effect size observed for G0 obesity (0.11; 95% CI, 0.080-0.14). Estimates of the direct effect were close to the null. In conclusion, grandmaternal prepregnancy BMI was associated with infant birthweight z score. Maternal prepregnancy BMI partly mediated the association, suggesting that factors related to BMI may play an important role in the transmission of weight across the maternal line.
本研究的目的是检验祖母（G0）孕前体重指数（BMI）对婴儿（G2）出生体重Z评分的总体影响，并量化母亲（G1）孕前BMI的中介作用。数据来自新斯科舍省三代多队列研究。使用g计算法估计G0孕前BMI与G2出生体重Z评分之间的关联以及G1孕前BMI的中介效应，并对通过有向无环图确定的混杂因素进行调整，同时考虑中间混杂因素。共纳入了来自18450名G0参与者的20822对G1 - G2母婴。与G0体重正常相比，G0体重过轻会降低G2出生体重Z评分的均值（-0.11；95%置信区间，-0.20至-0.030），而G0超重和肥胖则会增加G2出生体重Z评分的均值（分别为0.091 [95%置信区间，0.034 - 0.15]和0.22 [95%置信区间，0.11 - 0.33]）。G1孕前BMI部分介导了这种关联，其中G0肥胖的效应量最大（0.11；95%置信区间，0.080 - 0.14）。直接效应的估计接近零。总之，祖母孕前BMI与婴儿出生体重Z评分相关。母亲孕前BMI部分介导了这种关联，这表明与BMI相关的因素可能在跨母系的体重传递中起重要作用。
