神经管畸形高、低发区农村孕早期妇女血液叶酸水平比较研究

目的 了解神经管畸形高发区与低发区农村孕早期妇女血液叶酸状况。方法 采用现况调查方法对2003年神经管畸形高发与低发两个地区共688名农村孕早期妇女的血浆叶酸与红细胞叶酸水平进行研究。结果 高发区农村孕早期妇女血浆叶酸浓度（10．53nmol／L）与红细胞叶酸浓度（389．2nmol／L）中位数明显低于低发区妇女（血浆叶酸30．39nmol/L，红细胞叶酸926．0nmol／L），差异有统计学意义；高发区妇女血浆叶酸缺乏率约为50％，红细胞叶酸缺乏率约为43％，远高于低发区妇女（血浆叶酸6％，红细胞叶酸4％），差异有统计学意义；高、低发区服用叶酸组妇女血浆叶酸水平约为不服用组的2倍，红细胞叶酸水平是不服用组的1．4倍，差异有统计学意义；高、低发区服用叶酸组孕早期妇女的血浆缺乏率均低于不服用组，相对危险度（RR）值分别为0．60（95％CI：0．36～1．01）与0．16（95％CI：0．06～0．44），差异均有统计学意义；高、低发区服用叶酸组与不服用组红细胞叶酸缺乏率之间的RR值分别为0．64（95％CI：0．36～1．13）与0．39（95％CI：0．13～1．13），差异无统计学意义；服用叶酸的孕早期妇女中，低发区血浆叶酸水平约为高发区的1．7～1．9倍，红细胞叶酸水平约为高发区的2倍，差异有统计学意义；服用叶酸的孕早期妇女中，高发区血浆叶酸与红细胞叶酸缺乏率约为低发区的10～14倍，差异有统计学意义。结论 神经管畸形高发区农村孕早期妇女血液叶酸水平很低，增补叶酸可有效提高妇女血液叶酸水平、降低妇女叶酸缺乏率，高发区育龄妇女怀孕前后每日服用0．4mg叶酸的剂量可能不足，建议增加服用剂量。     

妊娠期妇女血液叶酸水平及影响因素分析

目的了解山西省部分地区妊娠期妇女血液叶酸水平及影响因素。方法研究对象来源于2013年至2017年在山西省平定、寿阳、太谷、泽州等县募集的孕中晚期妇女。采用问卷调查收集孕妇一般情况、膳食习惯、叶酸增补剂服用情况、末次月经日期、孕产史等,应用微生物法测定血浆和全血叶酸水平,采用中位数和第25～75百分位间距(P_(25),P_(75))表示叶酸浓度的平均水平。将血浆和红细胞叶酸浓度自然对数转换后引入多元线性回归模型,分析妊娠期妇女血液叶酸水平的可能影响因素。结果本研究共有234名妊娠期妇女纳入分析,妇女的平均全血叶酸浓度为399.1(250.0,590.1)nmol/L;平均血浆叶酸浓度为16.8(10.4,36.1)nmol/L;平均红细胞叶酸浓度为964.3(604.9,1 433.0)nmol/L。血浆叶酸缺乏率为25.6%,红细胞叶酸缺乏率为8.5%,47.6%的妊娠期妇女红细胞叶酸浓度低于906.0 nmol/L。90.1%的妇女服用含叶酸的增补剂,有效服用叶酸的妇女占20.9%。年龄、孕周、孕次、服用叶酸增补剂、水果摄入频率是妇女红细胞叶酸水平的影响因素。结论山西省部分地区妊娠期妇女的血液叶酸缺乏情况得到了一定改善,但血液叶酸浓度仍不理想,叶酸规范服用的科学性和依从性尚有待提高。     

叶酸预防神经管畸形效果分析

目的探讨妇女围孕期服用小剂量叶酸预防神经管畸形发生的效果。方法以1991年~1997年、1998年~2004年分娩的围产儿及其中的神经管畸形儿分别作为对照组和观察组,1997年8月~2004年12月围孕期服用小剂量叶酸制剂的妇女进行资料分析。结果围孕期服用小剂量叶酸制剂的妇女其神经管畸形发生数与对照组有显著性差异。结论妇女围孕期服用小剂量叶酸制剂可以明显降低神经管畸形的发生。     

叶酸预防神经管畸形的效果观察

[目的]观察妇女围孕期服用小剂量叶酸预防神经管畸形发生的效果.[方法]1993～1999年,2000～2006年分娩的围产儿及其中神经管畸形儿分别作为对照组和观察组,2000年1月～2006年12月围孕期服用小剂量叶酸制剂的妇女进行资料分析.[结果]围孕期服用小剂量叶酸的妇女其神经管畸形发生数与对照组差异有统计学意义.[结论]妇女围孕期服用小剂量叶酸制剂可以明显降低神经管畸形的发生.     

叶酸预防神经管畸形在相关人群中的知晓率及行为

目的：了解妇幼卫生人员、婚检妇女和孕妇对孕前和孕早期服用叶酸预防神经管畸形的知识掌握程度及相关行为。方法：根据不同的对象自行设计知识和行为调查问卷，由妇幼卫生人员、婚检妇女和孕妇自己填写，将结果进行χ^2检验和方差分析。结果：76．7％（155／202）的妇幼卫生人员知道服用叶酸可以减少神经管畸形的发生，26．7％（54／202）的知道叶酸应当从孕前开始服用，仅有5．9％（12／202）的人知道叶酸每天摄入的适当量是0．4mg-1mg，34.7%(70/202)的妇幼卫生人员推荐的剂量大于1mg；194名婚检妇女仅4人（2．1％）知道叶酸可以预防胎儿畸形，4人在服用叶酸增补剂，2人知道要从孕前服用；31．9％（67／210）的孕妇知道叶酸与神经管畸形的关系，16．2％（34／210）知道应从孕前服用，14．3％（30／210）孕妇在服用叶酸增补剂，仅4人（1．9％）真正从孕前开始服用。结论：妇女增补叶酸预防神经管畸形的知识还没有得到很好的普及，叶酸的服用率低。建议培训妇幼人员（特别是县乡级人员）正确指导妇女应用叶酸的知识和能力，加大婚前教育宣传力度，增加服用叶酸预防神经管畸形知识的知晓率。     

山西省妊娠20周内妇女血浆叶酸水平及影响因素研究

目的了解妊娠妇女血浆叶酸水平及其影响因素,为育龄及妊娠妇女制定干预措施提供科学依据。方法选取2016年1月-2016年8月在山西省妇幼保健院进行孕期保健的妊娠20周内的724名妇女,静脉血叶酸水平的测定采用改良微生物法。结果 724名孕妇的血浆叶酸平均水平为(38.5±42.9)nmol/L,缺乏率为4.4%(血浆叶酸10.5 nmol/L)。认为是否有必要服用叶酸、本次怀孕是否服用叶酸、末次月经前后一个月食用水果的次数、孕前体质指数、孕妇年龄是孕妇血浆叶酸缺乏的影响因素。结论妊娠20周内妇女血浆叶酸营养状况较好,我们应该针对不同人群开展有针对性的健康教育,提高妇女体内叶酸水平,保证母婴健康。     

妇女围孕期补充叶酸与多胎妊娠关系的研究进展

随机对照临床试验和人群干预试验证实,妇女围孕期增补叶酸可以降低后代神经管畸形危险性的70%～85%.1992年,美国健康与人类服务部公共卫生事务处建议：所有可能怀孕的妇女每日常规增补0.4 mg叶酸.随后,英国、加拿大等许多国家也提出了类似的建议.中国卫生部、计划生育委员会和全国妇联等有关部门和组织也在全国育龄妇女中推广增补叶酸.妇女增补叶酸预防胎儿神经管畸形应从孕前3个月开始,直至妊娠满3个月.但是,有许多妊娠不是计划的,并且准确计划妊娠是很困难的事.因此,许多妇女知道自己怀孕后才开始服用叶酸增补剂,但此时往往已经错过了预防胎儿神经管畸形的最佳时机（神经管在妊娠28天内形成）.针对这种情况,美国食品药品管理局制定了叶酸强化食品政策,要求自1998年1月1日起,所有强化食品中必须添加叶酸（140μg叶酸/100g面粉）.     

出生缺陷高发区与低发区孕早期妇女叶酸知信行现况比较

目的了解出生缺陷高发区与低发区孕早期妇女叶酸知信行状况.方法采用横断面调查与对比研究，对出生缺陷高发与低发4个地区共1554名孕早期妇女的叶酸知识的了解情况、服用叶酸增补剂的态度及叶酸增补剂服用情况进行了问卷调查。结果出生缺陷高发区孕早期妇女听说过叶酸的比例(农村22．7％、城市60．7％)、知道叶酸预防神经管畸形作用的比例(农村18．1％、城市51．5％)，低于出生缺陷低发区妇女(农村85．1％、城市85．6％；农村、城市76．1％)；对于叶酸增补剂最佳服用时期，高发区农村孕早期妇女知晓率为16．3％、城市为35．9％，低于出生缺陷低发区(农村68．2％、城市68．8％)；出生缺陷高发区妇女认为有必要服用叶酸增补剂的比例(农村20．4％、城市50．7％)远低于出生缺陷低发区(农村76．1％、城市79．7％)；出生缺陷高发区城市与农村妇女叶酸增补剂服用率仅为8．5％和31．1％，低于出生缺陷低发区(农村63．4％、城市67．5％)。结论出生缺陷高发区孕早期妇女叶酸知识缺乏，叶酸增补剂服用率低。应通过健康教育和宣传，提高出生缺陷高发区育龄妇女对叶酸的认识和增补率。     

奎屯垦区育龄妇女增补叶酸工作评价

在奎屯垦区3837名育龄妇女中推广使用叶酸增补剂，预防神经管畸形出生，服用了4年并进行了流行病学调查，垦区育龄妇女叶酸服用率达到了85．53％，叶酸知识知晓率超过95．92％，神经管畸形出生率由未服药前的3．28‰降为服药后的1．82‰，围产儿死亡率由服药前的18．43‰下降为服药后的13．29‰。此项工作的推广，有效地控制和减少了我区出生缺陷的发生，降低了围产儿死亡率，给垦区带来了一定的社会效益。     

叶酸水平与原因不明习惯性流产的关系

目的探讨妇女血液叶酸水平与原因不明习惯性流产之间的关系。方法采用病例对照研究方法,选取至少有2次连续自然流产史的非孕期妇女作为病例;选取年龄与病例组相近,生育过子女且无自然流产史的未孕妇女作为对照。采用调查问卷收集社会人口学以及其它因素;每名研究对象采集5ml静脉血,用微生物法检测血浆叶酸及红细胞叶酸水平。结果共募集合格病例63例,对照145例。原因不明习惯性流产组血浆叶酸和红细胞叶酸浓度[几何均值分别为（19．0±1．9）nmol／L和（772．1±2．1）nmol／L]低于对照组血浆叶酸和红细胞叶酸浓度[几何均值分别为（20．1±1．6）nmol／L和（815．8±1．8）nmol／L],但差异均无统计学意义（P〉0．05）;原因不明习惯性流产组血浆叶酸缺乏率和红细胞叶酸缺乏率高于对照组（P〈0．05）,但控制职业及文化程度后,2组比较,差异无统计学意义（P〉0．05）;不同临床特征之间习惯性流产妇女血浆叶酸和红细胞叶酸水平比较,差异均无统计学意义（P〉0．05）。结论尚不能认为血液叶酸水平低下为习惯性流产的危险因素。     

163例育龄妇女血液叶酸水平检测结果分析

目的:了解育龄妇女血液叶酸水平,为制定叶酸预防出生缺陷方案提供依据。方法:取163名育龄妇女空腹静脉血4 m l,用电化学发光方法测定血清叶酸和红细胞叶酸水平。结果:血清叶酸和红细胞叶酸的平均水平分别为(9.71±4.16)ng/L和(529.18±194.25)ng/L,缺乏率分别为11.04%和1.23%。分别有53.99%和58.28%的妇女血清叶酸、红细胞叶酸水平小于预防神经管畸形最佳浓度,农村育龄妇女高达74.51%。结论:云南省育龄妇女叶酸缺乏率不高,但有1/2妇女血液叶酸水平小于预防神经管畸形最佳浓度,孕前应结合改变膳食结构健康教育加强叶酸的补充,并重点关注农村育龄妇女。     

Red cell folate and predicted neural tube defect rate in three Asian cities

BACKGROUND: Periconceptional folic acid reduces neural tube defect (NTD) risk. Red blood cell folate concentration is inversely associated with NTD risk. In many countries there is a lack of information on NTD rates. Red cell folate status in women of childbearing age may be a surrogate for NTD rates and may be helpful in identifying countries or regions most likely to benefit from improved folate status. OBJECTIVE: To predict NTD rates using red cell folate concentrations in women of childbearing age living in three Asian cities Design: Cross-sectional convenience samples of non-pregnant women living in Beijing (n=220), Kuala Lumpur (n=389), and Jakarta (n=129). RESULTS: Red cell folate concentrations were highest (p<0.001) in women from Jakarta at 872 nmol/L (95% CI; 833, 910) followed by Kuala Lumpur at 674 nmol/L (95% CI: 644, 704) and lowest in Beijing at 563 nmol/L (95% CI: 524, 601). Accordingly, predicted NTD rates were highest in Beijing at 30/10000 (95% CI: 27, 33), followed by Kuala Lumpur at 24/10000 (95% CI: 22, 25), and lowest in Jakarta at 15/10000 (95% CI: 14,15). CONCLUSION: Our red blood cell folate data suggests that of the three cities improving the folate status of women in Beijing would have the greatest impact on NTD rates.     

Folic acid fortified milk increases blood folate and lowers homocysteine concentration in women of childbearing age

Daily consumption of 400 microg folic acid prior to conception and during early pregnancy is recommended for the prevention of neural tube defects (NTD). Strategies to increase folic acid consumption include supplements and fortified foods. Milk is consumed by women and can be fortified with folic acid but little is known about the effect of fortified milk on blood folate concentration in women of childbearing age. The objective of this study was to determine whether daily consumption of milk fortified with 375 microg folic acid increases blood folate and lowers homocysteine concentrations in women of childbearing age. Seventy-three non-pregnant women (aged 18-47 y) were randomized to receive either 75 g/d of a fortified or unfortified (control) milk powder for 12 weeks. Women who consumed the folic acid fortified milk had mean (95% CI) red blood cell and plasma folate concentrations that were 539 nmol/L (436, 641) and 35 nmol/L (30, 41) higher, respectively, than in the control group. Women drinking fortified milk had a 14% lower mean plasma homocysteine concentration at week 12 than women consuming the control milk. Daily consumption of fortified milk powder providing 375 microg folic acid increases blood folate and lowers homocysteine concentrations over 12 weeks in women of childbearing age. Daily consumption of fortified milk would be expected to reduce NTD risk.     

Geographical, seasonal and gender differences in folate status among Chinese adults

Low blood folate concentrations have been associated with cardiovascular disease, neural tube defects and selected cancers, but little is known about folate status in Chinese adults. In a cross-sectional study we measured the plasma and red blood cell folate concentrations in 2422 Chinese men and women aged 35 to 64 y, living in the North and South of China, who provided blood samples either in March or September of 2001. The geometric mean concentrations of plasma and red blood cell folate were lower among Northerners than Southerners (adjusted geometric means, 8.4 and 502, and 16.7 and 811 nmol/L, respectively) controlling for age, gender, season (spring and fall), area (urban and rural), BMI, multivitamin use, alcohol intake and current smoking status. We estimated that approximately 40% of the Northerners and approximately 6% of the Southerners had plasma folate concentrations lower than the 6.8 nmol/L (3 microg/L), and approximately 30% of the Northerners and approximately 4% of the Southerners had red blood cell folate concentrations lower than the 363 nmol/L (160 microg/L), levels used to define folate deficiency. Within each region, men had lower plasma folate concentrations than women (6.9 versus 9.8 nmol/L in the North, and 14.5 versus 19.6 nmol/L in the South). In men, current smokers had a higher risk of folate deficiency compared with nonsmokers [adjusted odds ratios, 1.9 (95% CI, 1.4-2.6) for plasma folate deficiency and 2.5 (95% CI, 1.7-3.6) for red blood cell folate deficiency (P < 0.001)]. Our findings suggest that a large proportion of Chinese adults have a low folate status, especially those living in northern China where 60% of the men are plasma folate deficient in the spring. Further studies are needed to elucidate the factors that influence folate concentrations among middle-aged Chinese and to evaluate possible intervention strategies.     

Fortification with low amounts of folic acid makes a significant difference in folate status in young women: implications for the prevention of neural tube defects.

BACKGROUND: Mandatory fortification of grain products with folic acid was introduced recently in the United States, a policy expected to result in a mean additional intake of 100 microgram/d. One way of predicting the effectiveness of this measure is to determine the effect of removing a similar amount of folic acid as fortified food from the diets of young women who had been electively exposed to chronic fortification. OBJECTIVE: The objective was to examine the effect on folate status of foods fortified with low amounts of folic acid. DESIGN: We investigated the changes in dietary intakes and in red blood cell and serum concentrations of folate in response to removing folic acid-fortified foods for 12 wk from the diets of women who reportedly consumed such foods at least once weekly (consumers). RESULTS: Consumers (n = 21) had higher total folate intakes (P = 0.002) and red blood cell folate concentrations (P = 0.023) than nonconsumers (women who consumed folic acid-fortified foods less than once weekly; n = 30). Of greater interest, a 12-wk intervention involving the exclusion of these foods resulted in a decrease in folate intake of 78 +/- 56 microgram/d (P < 0.001), which was reflected in a significant reduction in red blood cell folate concentrations (P < 0.05). CONCLUSIONS: Cessation of eating folic acid-fortified foods resulted in removing 78 microgram folic acid/d from the diet. Over 12 wk this resulted in a lowering of red blood cell folate concentrations by 111 nmol/L (49 microgram/L). This magnitude of change in folate status in women can be anticipated as a result of the new US fortification legislation and is predicted to have a significant, although not optimal, effect in preventing neural tube defects.     

Effects of once-a-week or daily folic acid supplementation on red blood cell folate concentrations in women

OBJECTIVE: Our aim was to determine if a once-a-week folic acid supplement increases women's red blood cell folate to concentrations (>905 nmol/l) that are associated with a low risk of bearing a child with a neural tube defect. DESIGN: Randomized control trial. SETTING: General community. SUBJECTS: In total, 114 nonpregnant women (18-40 y) volunteers, with red blood cell folate concentrations between 295 and 905 nmol/l at screening. INTERVENTION: Women were randomized to receive a once-a-week 2800 microg folic acid supplement, a daily 400 microg folic acid supplement or a daily placebo for 12 weeks. RESULTS: The mean (95% CI) red blood cell folate concentrations increased during the 12-week intervention from 608 (553-668) to 900 (828-978) in the weekly folic acid group (P<0.05) and from 615 (560-677) to 1053 (957-1158) nmol/l in the daily group (P<0.05) during the trial. At week 12, 49% of women ingesting the weekly folic acid supplement had red blood cell folate concentrations greater than 905 nmol/l compared to 74% of women ingesting the daily supplement. CONCLUSION: A once-a-week 2800 microg folic acid supplement can increase women's red blood cell folate to concentrations associated with a reduced risk of bearing a child with a neural tube defect, but is less effective than a 400 microg daily supplement. Use of a weekly folic acid supplement over at least 12 weeks before conception by women of child-bearing age may prevent neural tube defects. FUNDING: The Otago Medical Research Foundation (Laurenson Award). Healtheries (New Zealand) provided the supplements.     

Biochemical indicators of B vitamin status in the US population after folic acid fortification: results from the National Health and Nutrition Examination Survey 1999-2000

BACKGROUND: Mandatory folic acid fortification of cereal-grain products was introduced in the United States in 1998 to decrease the risk that women will have children with neural tube defects. OBJECTIVE: The objective was to determine the effect of folic acid fortification on concentrations of serum and red blood cell (RBC) folate, serum vitamin B-12, and plasma total homocysteine (tHcy) and methylmalonic acid (MMA) in the US population. DESIGN: Blood was collected from a nationally representative sample of approximately 7300 participants aged > or = 3 y in the National Health and Nutrition Examination Survey (NHANES) during 1999-2000 and was analyzed for these B vitamin-status indicators. The results were compared with findings from the prefortification survey NHANES III (1988-1994). RESULTS: The reference ranges (5th-95th percentiles) were 13.1-74.3 nmol/L for serum folate, 347-1167 nmol/L for RBC folate, and 179-738 pmol/L for serum vitamin B-12. For plasma tHcy and MMA, the reference ranges for serum vitamin B-12-replete participants with normal serum creatinine concentrations were 3.2-10.7 mumol/L and 60-210 nmol/L, respectively. The prevalence of low serum folate concentrations (<6.8 nmol/L) decreased from 16% before to 0.5% after fortification. In elderly persons, the prevalence of high serum folate concentrations (>45.3 nmol/L) increased from 7% before to 38% after fortification; 3% had marginally low serum vitamin B-12 concentrations (<148 pmol/L) and 7% had elevated plasma MMA concentrations (>370 nmol/L). Seventy-eight percent of the US population had plasma tHcy concentrations <9 micromol/L. CONCLUSIONS: Every segment of the US population appears to benefit from folic acid fortification. Continued monitoring of B vitamin concentrations in the US population is warranted.     

育龄妇女增补叶酸1.2mg/d对红细胞叶酸水平的影响

目的研究育龄妇女增补叶酸1.2 mg/d后红细胞叶酸水平达到预防胎儿神经管畸形(neural tube defects,NTDs)阈值所需的时间,旨在为计划外妊娠妇女提出合适的叶酸增补方案,有效预防胎儿NTDs。方法将志愿观察对象40例按随机数字法分为观察组和对照组,每组各20例。观察组的育龄妇女增补叶酸1.2 mg/d,对照组的育龄妇女以淀粉片为安慰剂。服药周期为28 d,每隔7 d抽样检测红细胞叶酸水平。结果观察组的红细胞叶酸水平在2~3周后906 nmol/L,对照组的红细胞叶酸水平在4周后仍保持在700 nmol/L左右。两组红细胞叶酸水平在给药1、2、3、4周后差异均有统计学意义(P0.05)。结论计划外妊娠妇女增补叶酸可考虑初始剂量为1.2 mg/d,待2周后体内红细胞叶酸浓度大幅提高,再更改为0.4 mg/d的剂量服食至孕3个月。此方案可有效缩短孕早期妇女红细胞叶酸水平提高的时间,预防胎儿NTDs。     

Increases in blood folate indices are similar in women of childbearing age supplemented with [6S]-5-methyltetrahydrofolate and folic acid

The natural diastereoisomer [6S]-5-methyltetrahydrofolate ([6S]-5-MTHF) may be a safer fortificant than folic acid for neural tube defect (NTD) prevention because it is unlikely to mask vitamin B-12 deficiency. An inverse relationship between NTD risk and blood folate concentrations has been reported. In this randomized, placebo-controlled, double-blind trial, we compared the effects of [6S]-5-MTHF and folic acid supplementation for 24 wk on plasma folate and red cell folate (RCF) in women of childbearing age (18-49 y). Women (n = 104) were randomly assigned to receive a supplement containing [6S]-5-MTHF (113 micro g/d), folic acid (100 micro g/d) or placebo. The mean estimated linear increase in plasma folate concentration was 0.3 [95% confidence interval (CI): 0.1, 0.5], and 0.4 (0.2, 0.6) nmol/(L. wk) in the [6S]-5-MTHF and folic acid groups, respectively. The mean estimated linear increase in RCF was 7.4 (95% CI: 4.5, 10.3), and 8.3 (4.4, 12.3) nmol/(L. wk) in the [6S]-5-MTHF and folic acid groups, respectively. There were no differences in the slopes between the [6S]-5-MTHF group and the folic acid group in either plasma folate (P = 0.48) or RCF (P = 0.70). At 24 wk, estimated mean increases in plasma folate concentrations were 6.9 (95% CI: 1.7, 12.2) and 9.2 (3.3, 15.1) nmol/L, and in RCF, 251 (143, 360) and 275 (148, 402) nmol/L, in the [6S]-5-MTHF and folic acid groups, respectively, relative to the placebo group. These data suggest that low dose [6S]-5-MTHF and folic acid supplementation increase blood folate indices to a similar extent. A steady state in the blood indices had not been reached by 24 wk.