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美国一项最新研究发现，妇女在孕前服用叶酸补充剂可大大降低早产的风险，而且服用时间不能少于1年。 美国得克萨斯大学研究人员在5月12日出版的《科学公共图书馆·医学》（PLoS Medicine）上报告说，他们对大约3.5万名孕妇以及她们的分娩情况进行了跟踪调查。 结果发现，如果妇女在孕前服用叶酸补充剂至少1年，在妊娠期28周至32周分娩的风险将降低50%。研究人员强调说，如果妇女孕前服用叶酸不足1年，她们早产的风险不会有所降低。 胎龄未满37周出生的新生儿被认为是早产儿。大多数早产儿体重都小于2.5千克，身体各器官系统发育尚不成熟，功能不健全，抵抗力较弱，所以早产儿成活率低于胎龄近40周的婴儿。另外，早产儿发育过程中易患呼吸疾病，学习能力较差，发育迟缓。 据统计，12%的美国新生儿为早产儿。此前研究发现，母亲体内叶酸水平低是造成早产的原因之一。 叶酸是B族维生素之一，是人体必需的维生素，其最重要的功能就是制造红血球和白血球，增强免疫能力。医学专家一直建议，女性孕前3个月开始额外补充叶酸，可大大减少婴儿的神经系统出现缺陷。 推荐原始出处： PLoS Med 6(5): e1000061. doi:10.1371/journal.pmed.1000061 Preconceptional Folate Supplementation and the Risk of Spontaneous Preterm Birth: A Cohort Study Radek Bukowski1*, Fergal D. Malone2, Flint T. Porter3, David A. Nyberg4, Christine H. Comstock5, Gary D. V. Hankins1, Keith Eddleman6, Susan J. Gross7, Lorraine Dugoff8, Sabrina D. Craigo9, Ilan E. Timor-Tritsch10, Stephen R. Carr11, Honor M. Wolfe12, Mary E. D'Alton13 1 University of Texas Medical Branch, Department of Obstetrics and Gynecology, Galveston, Texas, United States of America, 2 Royal College of Surgeons in Ireland, Department of Obstetrics and Gynecology, Dublin, Ireland, 3 University of Utah, Salt Lake City, Utah, United States of America, 4 The Fetal & Women's Center of Arizona, Scottsdale, Arizona, United States of America, 5 William Beaumont Hospital, Fetal Imaging Department, Royal Oak, Michigan, United States of America, 6 Mount Sinai Medical Center, Department of Obstetrics and Gynecology, New York, New York, United States of America, 7 Montefiore Medical Center–Albert Einstein College of Medicine, Department of Obstetrics & Gynecology and Women's Health, Bronx, New York, United States of America, 8 University of Colorado Health Sciences Center, Department of Obstetrics and Gynecology, Denver, Colorado, United States of America, 9 Tufts-New England Medical Center, Department of Obstetrics and Gynecology, Boston, Massachusetts, United States of America, 10 New York University Medical Center, School of Medicine, Department of Obstetrics and Gynecology, New York, New York, United States of America, 11 Brown University/Women & Infants' Hospital, Department of Obstetrics and Gynecology, Providence, Rhode Island, United States of America, 12 University of North Carolina at Chapel Hill, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina, United States of America, 13 Columbia University Medical Center, Department of Obstetrics and Gynecology, Maternal-Fetal Medicine, New York, New York, United States of America Background Low plasma folate concentrations in pregnancy are associated with preterm birth. Here we show an association between preconceptional folate supplementation and the risk of spontaneous preterm birth. Methods and Findings In a cohort of 34,480 low-risk singleton pregnancies enrolled in a study of aneuploidy risk, preconceptional folate supplementation was prospectively recorded in the first trimester of pregnancy. Duration of pregnancy was estimated based on first trimester ultrasound examination. Natural length of pregnancy was defined as gestational age at delivery in pregnancies with no medical or obstetrical complications that may have constituted an indication for delivery. Spontaneous preterm birth was defined as duration of pregnancy between 20 and 37 wk without those complications. The association between preconceptional folate supplementation and the risk of spontaneous preterm birth was evaluated using survival analysis. Comparing to no supplementation, preconceptional folate supplementation for 1 y or longer was associated with a 70% decrease in the risk of spontaneous preterm delivery between 20 and 28 wk (41 [0.27%] versus 4 [0.04%] spontaneous preterm births, respectively; HR 0.22, 95% confidence interval [CI] 0.08–0.61, p = 0.004) and a 50% decrease in the risk of spontaneous preterm delivery between 28 and 32 wk (58 [0.38%] versus 12 [0.18%] preterm birth, respectively; HR 0.45, 95% CI 0.24–0.83, p = 0.010). Adjustment for maternal characteristics age, race, body mass index, education, marital status, smoking, parity, and history of prior preterm birth did not have a material effect on the association between folate supplementation for 1 y or longer and spontaneous preterm birth between 20 and 28, and 28 to 32 wk (adjusted HR 0.31, 95% CI 0.11–0.90, p = 0.031 and 0.53, 0.28–0.99, p = 0.046, respectively). Preconceptional folate supplementation was not significantly associated with the risk of spontaneous preterm birth beyond 32 wk. The association between shorter duration (<1 y) of preconceptional folate supplementation and the risk of spontaneous preterm birth was not significant after adjustment for maternal characteristics. However, the risk of spontaneous preterm birth decreased with the duration of preconceptional folate supplementation (test for trend of survivor functions, p = 0.01) and was the lowest in women who used folate supplementation for 1 y or longer. There was also no significant association with other complications of pregnancy studied after adjustment for maternal characteristics. Conclusions Preconceptional folate supplementation is associated with a 50%–70% reduction in the incidence of early spontaneous preterm birth. The risk of early spontaneous preterm birth is inversely proportional to the duration of preconceptional folate supplementation. Preconceptional folate supplementation was specifically related to early spontaneous preterm birth and not associated with other complications of pregnancy. (责任编辑：Doctor001) |
