Abstract：
OBJECTIVE: Prenatal folate exposure may alter epigenetic marks in the offspring. We aimed to evaluate associations between prenatal exposure to folic acid (FA) in preconception and in utero with cord blood DNA methylation in long interspersed nuclear element 1 (LINE-1) and Alu short interspersed nuclear elements (SINEs) as markers of global DNA methylation levels.
METHODS: Data come from 325 mother-child pairs participating in the Nutrition in Early Life and Asthma (NELA) birth cohort (2015-2018). Pregnant women were asked about supplement use, including brand name and dose, one month before pregnancy (preconception) and through the trimesters of pregnancy. Maternal dietary folate intake was assessed using a validated food frequency questionnaire with additional questions for FA supplement use. Folate serum levels were measured in mothers at 24 weeks of gestation and in cord blood of newborns. DNA methylation was quantitatively assessed by bisulfite pyrosequencing on 5 LINE-1 and 3 Alu different elements. Associations were estimated using multivariable linear regression models.
RESULTS: A reduction in methylation levels of LINE-1 in newborns was associated with the use of FA supplements below the recommended doses (<400 ug/day) during preconception (-0.50; 95% CI: -0.91, -0.09; P = 0.016), and from preconception up to 12 weeks of gestation (-0.48; 95% CI: -0.88, -0.08; P = 0.018). Maternal use of FA supplements above the tolerable upper intake level of 1000 ug/day from preconception until 12 weeks of gestation was also related to lower methylation in LINE-1 at birth (-0.77; 95% CI: -1.52, -0.02; P = 0.044). Neither FA supplement use after 12 weeks of gestation nor maternal total folate intake (diet plus supplements) were associated with global DNA methylation levels at birth.
CONCLUSIONS: Maternal non-compliance with the use of FA supplement recommendations from preconception up to 12 weeks of gestation reduces offspring global DNA methylation levels at birth.
METHODS: Data come from 325 mother-child pairs participating in the Nutrition in Early Life and Asthma (NELA) birth cohort (2015-2018). Pregnant women were asked about supplement use, including brand name and dose, one month before pregnancy (preconception) and through the trimesters of pregnancy. Maternal dietary folate intake was assessed using a validated food frequency questionnaire with additional questions for FA supplement use. Folate serum levels were measured in mothers at 24 weeks of gestation and in cord blood of newborns. DNA methylation was quantitatively assessed by bisulfite pyrosequencing on 5 LINE-1 and 3 Alu different elements. Associations were estimated using multivariable linear regression models.
RESULTS: A reduction in methylation levels of LINE-1 in newborns was associated with the use of FA supplements below the recommended doses (<400 ug/day) during preconception (-0.50; 95% CI: -0.91, -0.09; P = 0.016), and from preconception up to 12 weeks of gestation (-0.48; 95% CI: -0.88, -0.08; P = 0.018). Maternal use of FA supplements above the tolerable upper intake level of 1000 ug/day from preconception until 12 weeks of gestation was also related to lower methylation in LINE-1 at birth (-0.77; 95% CI: -1.52, -0.02; P = 0.044). Neither FA supplement use after 12 weeks of gestation nor maternal total folate intake (diet plus supplements) were associated with global DNA methylation levels at birth.
CONCLUSIONS: Maternal non-compliance with the use of FA supplement recommendations from preconception up to 12 weeks of gestation reduces offspring global DNA methylation levels at birth.
摘要：
目的：产前叶酸暴露可能改变后代的表观遗传标记。我们旨在评估孕前和子宫内叶酸（FA）的产前暴露与长散布核元素1（LINE-1）和Alu短散布核元素（SINE）中的脐带血DNA甲基化之间的关系作为整体DNA甲基化水平的标志物。
方法：数据来自参与早期生命和哮喘营养（NELA）出生队列（2015-2018）的325对母子对。孕妇被问及补充剂的使用，包括品牌名称和剂量，怀孕前一个月（孕前）和怀孕的三个月。使用经过验证的食物频率问卷评估母亲的饮食叶酸摄入量，并附有有关FA补充剂使用的其他问题。在妊娠24周的母亲和新生儿脐带血中测量叶酸血清水平。通过亚硫酸氢盐焦磷酸测序对5个LINE-1和3个Alu不同元件定量评估DNA甲基化。使用多变量线性回归模型估计关联。
结果：新生儿LINE-1甲基化水平的降低与孕前使用FA补充剂低于推荐剂量（<400ug/天）有关（-0.50；95％CI：-0.91，-0.09；P=0.016），从孕前到妊娠12周（-0.48;95％CI：-0.88，-0.08;P=0.018）。从孕前到妊娠12周，母亲使用高于可耐受的上限摄入量1000ug/天的FA补充剂也与出生时LINE-1的甲基化降低有关（-0.77；95％CI：-1.52，-0.02；P=0.044）。妊娠12周后使用FA补充剂或母亲总叶酸摄入量（饮食加补充剂）均与出生时的整体DNA甲基化水平无关。
结论：孕妇在孕前至妊娠12周时不遵守FA补充建议可降低后代出生时的整体DNA甲基化水平。
方法：数据来自参与早期生命和哮喘营养（NELA）出生队列（2015-2018）的325对母子对。孕妇被问及补充剂的使用，包括品牌名称和剂量，怀孕前一个月（孕前）和怀孕的三个月。使用经过验证的食物频率问卷评估母亲的饮食叶酸摄入量，并附有有关FA补充剂使用的其他问题。在妊娠24周的母亲和新生儿脐带血中测量叶酸血清水平。通过亚硫酸氢盐焦磷酸测序对5个LINE-1和3个Alu不同元件定量评估DNA甲基化。使用多变量线性回归模型估计关联。
结果：新生儿LINE-1甲基化水平的降低与孕前使用FA补充剂低于推荐剂量（<400ug/天）有关（-0.50；95％CI：-0.91，-0.09；P=0.016），从孕前到妊娠12周（-0.48;95％CI：-0.88，-0.08;P=0.018）。从孕前到妊娠12周，母亲使用高于可耐受的上限摄入量1000ug/天的FA补充剂也与出生时LINE-1的甲基化降低有关（-0.77；95％CI：-1.52，-0.02；P=0.044）。妊娠12周后使用FA补充剂或母亲总叶酸摄入量（饮食加补充剂）均与出生时的整体DNA甲基化水平无关。
结论：孕妇在孕前至妊娠12周时不遵守FA补充建议可降低后代出生时的整体DNA甲基化水平。
