House J D, March S B, Ratnam S, Ives E, Brosnan J T, Friel J K
Department of Animal Science, University of Manitoba, Winnipeg.
CMAJ. 2000 May 30;162(11):1557-9.
Newfoundland has one of the highest rates of neural tube defects in North America. Given the association between low maternal folic acid levels and neural tube defects, a cross-sectional study was conducted to obtain base-line data on the folate and vitamin B12 status of a sample of women in Newfoundland who were pregnant.
Blood samples were collected between August 1996 and July 1997 from 1424 pregnant women in Newfoundland during the first prenatal visit (at approximately 16 weeks' gestation); this represented approximately 25% of the women in Newfoundland who were pregnant during this period. The samples were analysed for serum folate, vitamin B12, red blood cell folate and homocysteine.
Median values for serum folate, red blood cell folate and serum vitamin B12 were 25 nmol/L, 650 nmol/L and 180 pmol/L, respectively. On the basis of the interpretive criteria used for red blood cell folate status, 157 (11.0%) of the 1424 women were deficient (< 340 nmol/L) and a further 180 (12.6%) were classified as indeterminate (340-420 nmol/L). Serum homocysteine levels, measured in subsets of the red blood cell folate status groups, supported the inadequate folate status. Serum vitamin B12 levels of 621 (43.6%) women were classified as deficient or marginal; however, the validity of the interpretive criteria for pregnant women is questionable.
A large proportion of pregnant women surveyed in Newfoundland in 1997 had low red blood cell folate levels.
纽芬兰是北美地区神经管缺陷发生率最高的地区之一。鉴于孕妇叶酸水平低与神经管缺陷之间的关联，开展了一项横断面研究，以获取纽芬兰孕妇样本中叶酸和维生素B12状况的基线数据。
在1996年8月至1997年7月期间，从纽芬兰的1424名孕妇首次产前检查（约妊娠16周）时采集血样；这约占该时期纽芬兰孕妇总数的25%。对样本进行血清叶酸、维生素B12、红细胞叶酸和同型半胱氨酸分析。
血清叶酸、红细胞叶酸和血清维生素B12的中位数分别为25 nmol/L、650 nmol/L和180 pmol/L。根据用于评估红细胞叶酸状况的解释标准，1424名女性中有157名（11.0%）缺乏（<340 nmol/L），另有180名（12.6%）被归类为不确定（340 - 420 nmol/L）。在红细胞叶酸状况分组的子集中测量的血清同型半胱氨酸水平支持叶酸状况不足。621名（43.6%）女性的血清维生素B12水平被归类为缺乏或边缘状态；然而，用于孕妇的解释标准的有效性值得怀疑。
1997年在纽芬兰接受调查的很大一部分孕妇红细胞叶酸水平较低。
