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  3. Taking a multivitamin around the time of conception may help women lower their risk of delivering low-birth-weight babies, a new

Taking a multivitamin around the time of conception may help women lower their risk of delivering low-birth-weight babies, a new

admin2015-09-30  49
问题     Taking a multivitamin around the time of conception may help women lower their risk of delivering low-birth-weight babies, a new research shows. The study, one of the first to look at multivitamin use immediately before and after conception, strengthens the notion that nutritional deficiencies may increase the risk of birth complications.
    Still, the researchers cautioned that it was too soon to recommend multivitamins for women who are contemplating pregnancy or already expecting. While some studies have suggested benefits, others have found that women who eat a healthy diet have no need for multivitamins, and that vitamins may even do some harm, especially when their use is continued late into a pregnancy.
    The study, published in the September issue of The American Journal of Clinical Nutrition, analyzed data on nearly 36,000 Danish women enrolled in a national birth registry. The scientists who carried out the research found that a large share of the women—about 60 percent had been taking multivitamins in the four weeks before and eight weeks after the last menstrual period. After adjusting for a number of risk factors, like smoking, weight and the age of the mother, the study found that women who took a daily multivitamin and were of normal weight had a nearly 20 percent lower chance of delivering a preterm baby, compared with those who did not take a daily multivitamin. Women who were overweight did not see the same benefit, though it was unclear why.
    In 2004, a study by scientists at Emory University and the Centers for Disease Control and Prevention found that taking daily multivitamins was a widespread practice among expectant mothers in the United States. Up to 78 percent of pregnant women reported taking multivitamins, the study found, compared with only 47 percent of women who were not pregnant.
    Doctors have long encouraged pregnant women and those contemplating pregnancy to take folic acid—a B vitamin—daily to help prevent neural tube defects. Folic acid is the synthetic form of folate, a member of the family of B vitamins that is involved with DNA synthesis and DNA methylation. Because of these crucial functions, folate plays important roles in fetal development and nerve tissue health. And since the late 1990s, the government has also required food makers to add the vitamin to many grain products, including flour and breads. The authors of the latest study suggested that there could be other nutrients in multivitamins besides folic acid that help reduce the risk of birth complications. But they also said that more, research was needed, and that they were not recommending that women trying to conceive should start a daily multivitamin regimen.
The main idea of the passage is that______.
选项 A、taking a multivitamin around the time of conception may help women lower their risk of delivering low birth-weight babies
B、women who took a daily multivitamin had a nearly 20 percent lower chance of delivering a preterm baby
C、women trying to conceive should start a daily multivitamin regimen
D、a new research strengthens the notion that taking multivitamins may decrease the risk of birth complications
答案D
解析 本题考查考生对全文大意的概括和理解。文章对一项基于丹麦36，000名孕妇数据的研究结果做了介绍，发现每天服用多种维生素剂的孕妇产出早产儿的可能性更小，并且有可能帮助减少分娩并发症的风险。其实很多时候，文章的第一段往往就是全文的概括和总结，本文也不例外。第一段便是全文的概括，而D选项又是对第一段内容的概括，因此是正确选项。A和B都是文中出现的观点，属于孕期服用多种维生素带来的好处，分别针对产出体重过低婴儿和早产儿两种危险，但是都是片面的，没有全面总结，而且没有提到这项研究。C本身就是错误的观点，文中虽然指出服用多种维生素可能带来好处，但是在最后一段结尾处明确指出，可能存在另外的原因能帮助减少分娩并发症风险，他们表示这需要更多的研究，因而并不建议准备要怀孕的妇女应该开始每天服用多种维生素剂。因此C也错误。
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