Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China.
Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing, P. R. China.
Int J Epidemiol. 2019 Dec 1;48(6):2010-2017. doi: 10.1093/ije/dyz130.
Folic acid (FA) supplementation prevents neural tube defects, but there are mixed results for its ability to prevent limb reduction defects. We examined whether a preventive effect of FA supplementation exists for congenital limb reduction defects in a large population in China.
Data from a large population-based cohort study in China were used to evaluate the effects of FA supplementation on birth defects. All births at 20 complete gestational weeks, including live births, stillbirths and pregnancy terminations, and all structural congenital anomalies, regardless of gestational week, were recorded. A total of 247 831 singleton live births delivered at gestational ages of 20-42 weeks to women from northern and southern China with full information on FA intake were included. Limb reduction defects were classified by subtype and maternal FA supplementation.
The prevalence of limb reduction defects was 2.7 per 10 000 births among women who took FA compared with 9.7 per 10 000 births among those who did not take FA in northern China; the prevalence was 4.5 and 3.8 per 10 000 births, respectively, in southern China. In both unadjusted and adjusted analyses, the estimated relative risk for upper limb reduction defects [odds ratio (OR) = 0.17, 95% confidence interval (CI): 0.04, 0.63] and total limb reduction defects (OR = 0.24, 95% CI: 0.08, 0.70) in northern China, but not for lower limb reduction defects ,was significantly decreased in association with FA supplementation in northern China. There was no association between FA supplementation and either an increased or decreased risk for limb reduction defects in southern China.
FA supplementation successfully reduces the prevalence of limb reduction defects in northern China, whose population has low folate concentrations.
叶酸（FA）补充可预防神经管缺陷，但对于其预防肢体缺陷的能力存在混合结果。我们在中国的一个大人群中研究了 FA 补充是否存在预防先天性肢体缺陷的作用。
我们使用中国一项大型基于人群的队列研究的数据来评估 FA 补充对出生缺陷的影响。所有在 20 个完整孕周的活产儿、死产儿和妊娠终止以及所有结构先天性异常，无论孕周如何，均进行记录。共有 247831 例单胎活产儿纳入研究，这些婴儿的母亲来自中国北方和南方，她们在妊娠 20-42 周时摄入了 FA，且资料完整。根据亚类和母亲 FA 补充情况对肢体缺陷进行分类。
在中国北方，服用 FA 的女性肢体缺陷的患病率为 2.7/10000 活产儿，而未服用 FA 的女性为 9.7/10000 活产儿；在南方，患病率分别为 4.5/10000 活产儿和 3.8/10000 活产儿。在未调整和调整分析中，北方地区上肢肢体缺陷（比值比[OR] = 0.17，95%置信区间[CI]：0.04，0.63）和总肢体缺陷（OR = 0.24，95%CI：0.08，0.70）的估计相对风险均显著降低，与 FA 补充有关，但下肢肢体缺陷的风险没有降低。在南方，FA 补充与肢体缺陷的风险增加或降低均无关。
FA 补充成功降低了中国北方肢体缺陷的患病率，而北方人群的叶酸浓度较低。
