De Wals Philippe, Tairou Fassiatou, Van Allen Margot I, Lowry R Brian, Evans Jane A, Van den Hof Michiel C, Crowley Marian, Uh Soo-Hong, Zimmer Pamela, Sibbald Barbara, Fernandez Bridget, Lee Nora S, Niyonsenga Theophile
Department of Social and Preventive Medicine, Laval University, Quebec City, QC, Canada.
Birth Defects Res A Clin Mol Teratol. 2008 Sep;82(9):622-6. doi: 10.1002/bdra.20485.
In 1998, fortification of a large variety of cereal products with folic acid became mandatory in Canada. A multicentric study was carried out to assess the impact of this policy on the frequency of NTDs. The present analysis focused on spina bifida.
The study population included approximately 2 million livebirths, stillbirths, and terminations of pregnancies because of fetal anomalies among women residing in seven Canadian provinces, from 1993 to 2002. Spina bifida cases were divided according to the upper limit of the defect: upper (cranial, cervical, or thoracic) and lower (lumbar or sacral) defects. Based on published results of red blood cell folate tests, the study period was divided into prefortification, partial fortification, and full fortification periods.
A total of 1,286 spina bifida cases were identified: 51% livebirths, 3% stillbirths, and 46% terminations. Prevalence decreased from 0.86/1,000 in the prefortification to 0.40 in the full fortification period, while the proportion of upper defects decreased from 32% to 13%. Following fortification, regional variations in the prevalence and distribution of sites almost disappeared.
Results confirmed the etiologic heterogeneity of spina bifida and the more pronounced effect of folic acid in decreasing the risk of the more severe clinical presentations.
1998年，加拿大强制要求在多种谷物产品中强化叶酸。开展了一项多中心研究，以评估该政策对神经管缺陷发生率的影响。本分析聚焦于脊柱裂。
研究人群包括1993年至2002年居住在加拿大七个省份的妇女所生的约200万活产儿、死产儿以及因胎儿异常而终止的妊娠。脊柱裂病例根据缺陷的上限进行划分：上（颅、颈或胸）部和下（腰或骶）部缺陷。根据红细胞叶酸检测的已发表结果，将研究期分为强化前、部分强化和完全强化期。
共识别出1286例脊柱裂病例：51%为活产儿，3%为死产儿，46%为终止妊娠。患病率从强化前的0.86/1000降至完全强化期的0.40，而上部缺陷的比例从32%降至13%。强化后，患病率和部位分布的区域差异几乎消失。
结果证实了脊柱裂的病因异质性，以及叶酸在降低更严重临床表现风险方面更显著的效果。
