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本文选自《华盛顿邮报》10月22日文章。怀孕和分娩会对女性的身体、荷尔蒙和生理造成重大影响，这一过程似乎与女性随后对衰老过程有关，以往的研究对此有不同的结论，一些研究表明，怀孕和分娩在细胞水平上显著加速了女性的衰老，然而也有一些研究表明，怀孕和分娩可能会延缓女性衰老过程。最近发表在《科学报告》杂志上一篇文章，从DNA的角度研究怀孕和分娩对女性衰老过程的影响，研究发现，女性每一次怀孕，成为母亲的女性的端粒比没有孩子的同龄人大4个月到4岁，端粒是染色体末端的一小段DNA-蛋白质复合体，其长度会随着人体年龄的增长而缩短，当端粒过短，细胞就会死亡并停止复制，端粒越短，患心血管疾病、癌症、糖尿病和其他健康疾病的风险就越大。这表明，怀孕和分娩会加速女性衰老过程。此外，该研究还通过测量从白细胞中提取的DNA中的细胞数量，来观察女性的表观遗传年龄，其结果也印证了上述研究结果：女性怀孕次数越多，她的表观遗传年龄就越“老”。 
选文精讲 Examining pregnancy and its role in aging
Women undergo significant physical, hormonal and physiological changes during pregnancy and childbirth. Now, researchers are trying to understand how these major life events affect the female aging process that follows.
在怀孕和分娩期间，女性的身体、荷尔蒙和生理会经历重大变化。现在，研究人员正试图了解这些重大的人生经历，是如何影响女性随后的衰老过程的。 The research is still in its early stages and is a broad area involving the investigation of several biological markers of aging. These include telomeres, or the end caps of chromosomes that have been shown to shorten as we age; epigenetics, the study of whether certain genes get turned on and off; and microchimerism, a fascinating phenomenon where cells from mom and baby go back and forth across the placenta during pregnancy, with some colonizing long-term in one or both bodies.telomere: 端粒，是存在于真核细胞线状染色体末端的一小段DNA-蛋白质复合体，它与端粒结合蛋白一起构成了特殊的“帽子”结构，作用是保持染色体的完整性和控制细胞分裂周期。端粒其长度反映细胞复制史及复制潜能，被称作细胞寿命的“ 有丝分裂钟”。- microchimerism: 微嵌合，由于某一个体的少量细胞转移到另一个体内所造成的。多见于怀孕妇女及器官移植受体中。
- go back and forth: 来来回回，来回穿梭
- colonize: 开辟殖民地、占领，这里指“留在...中”
该研究仍处于早期阶段，是涉及多个衰老生物学标记的广泛研究，其中包括端粒，即染色体的端帽，随着年龄的增长，端粒会缩短；表观遗传学，研究某些基因是否触发或关闭；还有非常有趣的微嵌合体现象，在怀孕期间，来自母亲和婴儿的细胞在胎盘中来回穿梭，有些交换的细胞会长期留存在母体或孩子体内。 So far, the results are varied. Some studies report that pregnancy and childbirth dramatically accelerate aging in women at the cellular level. Other research, though, suggests that motherhood and pregnancy may slow down the aging process.到目前为止，结果各不相同。一些研究称，怀孕和分娩在细胞水平上显著加速了女性的衰老。然而，其他研究表明，成为母亲和怀孕可能会延缓衰老过程。 These types of contradictions are bound to be found during the early stages of research, said Dan Eisenberg, a biological anthropologist at the University of Washington, who does work in the area.华盛顿大学的生物人类学家丹·艾森伯格就研究该领域，他说，这类矛盾肯定会在研究的早期阶段出现。 “Any single study could be wrong even when the scientists are doing everything right,” he said. “Part of the way that science works is that people look at similar questions all around the world. Then we combine those studies to look at trends and narrow in on what is true.”“任何一项研究都可能是错误的，即使科学家们做的每件事都是正确的，”他说。“科学工作的部分方式是，世界各地的人在关注类似的问题，然后我们把这些研究结合起来，观察趋势，缩小范围，确定哪些是正确的。” Last year, Eisenberg and his colleagues published a paper in the journal Scientific Reports, which found that with each pregnancy a mother’s telomeres appear to be about four months to four years older than those of her peers without children.去年，艾森伯格和他的同事们在《科学报告》杂志上发表了一篇论文，发现每一次怀孕，成为母亲的女性的端粒似乎都比没有孩子的同龄人大4个月到4岁。 Telomeres sit at the end of chromosomes, the threadlike structures that contain our genetic material. Telomeres are kind of like the hard end of shoelaces and serve as a form of protection for the chromosome. When telomeres get too short, cells die and stop replicating. Shorter telomeres are associated with an increased risk of cardiovascular disease, cancer, diabetes and other health conditions. Although telomeres are known to shorten in all humans with age, certain things, such as cigarette smoking, a high body mass index and major stress may accelerate the shortening process. Good sleep, regular exercise and a Mediterranean diet have been associated with longer telomeres.端粒位于染色体的末端，是包含遗传物质的线状结构。端粒有点像鞋带的末端硬质橡胶，是保护染色体的一种形式。当端粒过短，细胞就会死亡并停止复制。端粒越短，患心血管疾病、癌症、糖尿病和其他健康疾病的风险就越大。尽管端粒会随着年龄的增长而缩短，但某些事情，如吸烟、高体重指数和巨大压力可能会加速端粒缩短的过程。良好的睡眠、有规律的锻炼和地中海式的饮食，与长端粒有关。 The study also looked at the epigenetic age of women, a measurement taken by looking at DNA extracted from white blood cells. By studying the population of cells in the DNA, researchers can determine a person’s epigenetic age. The results were similar to what the telomeres indicated: The more pregnancies a woman went through, the “older” her epigenetic age.该研究还通过对从白细胞中提取的DNA的测量，观察女性的表观遗传年龄。通过研究DNA中的细胞数量，研究人员可以确定一个人的表观遗传年龄。其结果与端粒显示的结果相似：女性怀孕次数越多，她的表观遗传年龄就越“老”。 
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