Carretti N, Eremita G A, Porcelli B, Paternoster D, Grella P
Clinica Ostetrica e Ginecologica, Università di Siena, Italia.
Gynecol Obstet Invest. 1994;38(2):78-81. doi: 10.1159/000292453.
The aim of this study was to evaluate folate and vitamin B12 serum concentrations and their reciprocal relationships during pregnancy in relation to gestational age and levels of hemoglobin. Serum levels of vitamin B12 (B12) and folic acid (FA) were assessed by RIA in 213 women between the 6th and 43rd week of pregnancy. For 195 of these subjects, hemoglobin and hematocrit values were available. The logarithm (log) of B12 levels was found to be inversely correlated with weeks of pregnancy (R = -0.261; p < 0.001). A decrease in B12 levels occurred before the 27th week and was significant only in the subgroup of patients having hemoglobin levels above 11 g/dl. The log FA concentrations did not show any significant correlation with weeks of pregnancy irrespective of Hb levels. There was also a highly significant correlation between log B12 and log FA after 27 weeks and in the subgroups divided according to Hb levels (< or = and > 11 g/dl). It is therefore concluded that: (1) the demand for vitamin B12 is high in the first 27 weeks of pregnancy due to increasing maternal and embryo-fetal erythropoiesis and in order to sustain normal maternal Hb levels in the last weeks of pregnancy; (2) vitamin B12 might favor the absorption and utilization of FA after 27 weeks of pregnancy.
本研究旨在评估孕期血清叶酸和维生素B12浓度及其相互关系，以及与孕周和血红蛋白水平的关系。采用放射免疫分析法（RIA）对213名孕周在6至43周的孕妇进行血清维生素B12（B12）和叶酸（FA）水平检测。其中195名受试者有血红蛋白和血细胞比容值。发现B12水平的对数与孕周呈负相关（R = -0.261；p < 0.001）。B12水平在第27周前下降，且仅在血红蛋白水平高于11 g/dl的患者亚组中具有显著性。无论血红蛋白水平如何，FA浓度对数与孕周均无显著相关性。在27周后以及根据血红蛋白水平（≤和>11 g/dl）划分的亚组中，B12对数与FA对数之间也存在高度显著相关性。因此得出结论：（1）由于母体和胚胎 - 胎儿红细胞生成增加，且为了在孕期最后几周维持母体正常血红蛋白水平，孕期前27周对维生素B12的需求量较高；（2）孕期27周后维生素B12可能有利于叶酸的吸收和利用。
