无锡地区早期妊娠妇女血液叶酸浓度季节变化趋势及影响因素

目的了解无锡地区早期妊娠妇女血液叶酸浓度,观察血液叶酸浓度随季节变动趋势,分析血液叶酸浓度的影响因素。方法研究对象为孕12周内妇女。采用面对面调查方法收集资料,每名妇女采集非空腹静脉血4ml测定血浆叶酸和红细胞叶酸浓度。采用逐步回归方法筛选血液叶酸浓度的影响因素。采用协方差分析,计算调整相关混杂因素后不同季节以及服用和不服用叶酸增补剂者的血液叶酸浓度。结果2002年12月至2003年11月共募集早期妊娠妇女596名。血浆叶酸和红细胞叶酸浓度的几何均数分别为34．1 nmol／L和902．8 nmol／L,缺乏率分别为3．0％和2．4％。但50％早期妊娠妇女的红细胞叶酸浓度低于预防神经管畸形的最佳水平(906 nmol／L)。血浆叶酸浓度4～6月最低;红细胞叶酸浓度1-3月最低。围受孕期服用叶酸增补剂可以显著提高血浆叶酸浓度和红细胞叶酸浓度;血浆叶酸浓度和红细胞叶酸浓度随妇女年龄增加而升高;农村早期妊娠妇女的血浆叶酸浓度低于城市早期妊娠妇女;每日食用1次及以上水果者的红细胞叶酸浓度高于水果食用频率不足每日1次者。对年龄和居住地调整后,围受孕期服用叶酸增补剂妇女的血浆叶酸浓度比未服用者高1倍以上(P<0．001);对年龄和食用水果频率调整后,服用叶酸增补剂妇女的红细胞叶酸浓度比未服用者高42％(P<0．001)。结论无锡地区早期妊娠妇女叶酸缺乏率不高,但有50％早期妊娠妇女的红细胞叶酸浓度低于预防胎儿神经管畸形的最佳水平。红细胞叶酸浓度1—3月处于低谷,此时受孕,胎儿神经管畸形的危险性将增加。围受孕期服用叶酸增补剂可显著提高血液叶酸浓度。在制订育龄妇女增补叶酸计划时,应结合改变膳食教育,并应重点关注农村妇女。

Blood folate concentrations, seasonal variations and associated factors among women in their first trimester of pregnancy in Wuxi, China

Objective To characterize blood folate status and its seasonal trend and to explore factors associated with blood folate concentrations among early pregnant women in Wuxi, China. Methods Subjects were women in their first trimester of pregnancy. A face-to-face questionnaire was adminis-tered to each woman. 4 ml venous blood was drawn and plasma and red cell folate concentrations were determined with a microbiological method. Stepwise regression was used to identify factors associated with plasma or red cell folate concentrations, and analysis of covariance was used to compute blood folate concentrations and folate deficiency rate by folic acid status adjusting for other potential confounding factors. Results Five hundred and ninety-six women were recruited between December 2002 and November 2003. Geometric mean of plasma folate was 34.1 nmol/L (95 % CI: 32.4 - 36.0 nmol/L) and red cell folate 902.8 nmol/L (95 % CI: 870.4 - 936.5 nmol/L). Three percent and 2.4 % of women were plasma folate and red cell folate deficient respectively. About half (49.9 %) of women had red cell folate concentrations lower than 906 nmol/L, the optimal level for the prevention of folate-responsive neural tube defects. While plasma folate level was lowest in April through June, the lowest level of red cell folate was seen in January through March. Periconceptional use of folic acid and age were positively associated with both plasma and red cell folate concentrations. In addition, women living in urban cities had higher levels of plasma folate than women living in rural areas, and those who consumed one or more servings of fruits per day had higher levels of red cell folate than those who consumed less frequently. Compared with women who did not take folic acid, women who took folic acid had 100 % higher plasma folate concentrations (P< 0.001) after age and residence were adjusted for, and 42 % higher red cell folate concentrations (P< 0.001) after age and frequency of fruit consumption was adjusted for. Conclusion Although not so many early pregnant women were blood folate deficient, half of them had red cell folate levels lower than the optimal level for the prevention of folate-responsive neural tube defects, and red cell folate level was lowest in January through March. Periconceptional supplementation with folic acid can substantially increase blood folate concentrations. In planning folic acid promotion programs, dietary modification should be integrated and special attention should be paid to women living in rural areas.