摘要目的 了解中国北方农村地区孕晚期妇女及其新生儿的血浆叶酸水平,并评价两者的关联性.方法 2009年5-6月在河北省元氏和乐亭县募集孕妇并观察至分娩.募集时收集一般资料,临产前采集孕妇静脉血,分娩时采集新生儿脐带血,获得资料完整的孕妇与新生儿437对.采用微生物法检测血浆叶酸.孕妇血浆叶酸缺乏定义为血浆叶酸＜6.8 nmol/L,低于脐带血血浆叶酸水平第10百分位数者定义为新生儿叶酸相对缺乏.采用t检验和方差分析比较血浆叶酸水平,x2检验比较血浆叶酸缺乏率；采用logistic回归估计孕妇血浆叶酸缺乏与否与新生儿血浆叶酸相对缺乏的发生风险,进一步按孕妇血浆叶酸水平的五分位数分5组,采用线性回归探讨孕妇与新生儿两者的血浆叶酸水平是否存在剂量关系.采用Pearson相关系数描述新生儿和孕妇血浆叶酸水平的比值和孕妇血浆叶酸水平的关系.结果 孕晚期妇女血浆叶酸平均水平为8.0(95％CI:7.6～8.5)nmol/L,缺乏率为29.3％；新生儿血浆叶酸平均水平为24.0(95％CI:23.1 ～25.0) nmol/L,缺乏率为0.9％.新生儿血浆叶酸水平是孕妇的3.0倍(t=32.519,P＜0.01)；新生儿血浆叶酸缺乏率远低于孕妇(x2=137.2,P＜0.01).调整年龄、体重指数、地区、职业和文化程度后,孕妇血浆叶酸缺乏组的新生儿叶酸相对缺乏的发生风险是正常组的1.96(95％CI:1.02 ～ 3.80)倍；新生儿血浆叶酸水平随孕妇血浆叶酸水平的升高而上升(趋势检验P＜0.05).新生儿和孕妇血浆叶酸水平的比值与孕妇血浆叶酸水平呈负相关(r=-0.810,P＜0.001).结论 中国北方农村新生儿叶酸营养状况远好于孕晚期妇女；孕晚期妇女与新生儿血浆叶酸水平间存在剂量梯度关系；胎盘对叶酸的主动转运能力随着孕妇血浆叶酸水平的降低而增加.

abstractsObjective To study the plasma folate concentrations in the third trimester of pregnant women and newborn babies so as to assess the association between them.Methods Pregnant women in Yuanshi and Laoting counties in Hebei province from May to June in 2009 were recruited with related information collected at enrollment.Those pregnant women being enrolled were followed up until delivery.Maternal blood was collected before delivery,and cord blood was collected after the expulsion of the placenta.Data from 437 pairs of women and newborns were analyzed.Plasma folate concentration was measured by Microbiological assay,with maternal plasma folate concentration ＜6.8 nmol/L defined as folate deficiency.Neonatal plasma folate concentration below 10％ was defined as relative deficiency.Student t-test and ANOVA were used to compare the plasma folate concentrations between the groups and x2 test was used to compare the situation of folate deficiency.In order to assess the association between maternal and newborn folate levels,logistic regression analysis was used to estimate the odds ratio of the neonatal plasma folate relative deficiency between the maternal folate deficient and normal groups after adjusting factors as age,BMI,region,career and education.Linear regression was used to test the trend by quintiles of maternal plasma folate concentration.Pearson' s test was used to test the relationship between the ratio of neonatal and maternal plasma folate level and the level of maternal plasma folate.Results The geometric mean of maternal plasma folate concentration was 8.0(95％CI:7.6-8.5) nmol/L and the deficiency was 29.3％,but in newborn babies,they were 24.0(95％CI:23.1-25.0) nmol/L and 0.9％ respectively.The plasma folate level in newborn babies was 3.0 times as high as in maternal (t=32.519,P＜0.01 )but the neonatal plasma folate deficiency status was higher than in matemal ( x2=137.2,P＜0.01 ).When compared with the normal plasma folate level group,the risk on neonatal plasma folate relative deficiency in the maternal folate deficiency group was significantly higher aiter adjusted for confounders (OR=1.96,95％CI:1.02-3.80).The neonatal plasma folate level significantly increased along with the maternal plasma folate level (Ptrend＜0.05).The ratio of neonatal and maternal plasma folate level was significantly inversely correlated with the maternal folate level (r=-0.810,P＜0.001 ).Conclusion Folate status in newborns was much better than in their mothers',in the northern rural areas of China.The maternal folate status was positively correlated with their offspring' s.Active placental transport for folate was significantly increasing when the maternal plasma folate level decreased.