文章來源:未知 文章作者:enread 發布時間:2020-04-08 06:07 字體: [ ]  進入論壇

Women who give birth may be biologically "older" than women who don't, a new study suggests.
For the study, the researchers analyzed1 information from 1,556 US women ages 20 to 44 who took part in a national survey from 1999 to 2002, which involved giving blood samples.
The researchers looked at the genetic2 material inside the women's cells, specifically the length of their telomeres. These are caps on the ends of chromosomes3 that protect the chromosomes from damage. Telomeres naturally shorten as people age, but the structures don't shorten at the same rate in every person. The longer a person's telomeres are, the more times their cells could hypothetically still divide, research has shown. Thus, telomeres are considered a marker of biological age — that is, the age of a person's cells, rather than the individual's chronological4 age.
Women in the survey who said they'd given birth to at least one child had telomeres that were about 4 percent shorter, on average, than those of women who'd never given birth. The findings held even after the researchers took into account other factors that could affect telomere length, including the women's chronological age, body mass index and smoking habits.
These findings suggest that a "history of live birth may be associated with shorter telomeres," the researchers wrote in their abstract, which was presented at the meeting of the American Public Health Association in Denver.
The study was not designed to determine the reason behind the link, the researchers said. But one hypothesis is that having children increases stress levels, and high stress has been linked with shorter telomeres, the scientists said.
"It is possible that pregnancy5, birth and child-rearing can induce chronic6 stress, leading to shorter telomere length perhaps through an inflammatory pathway," said study researcher Anna Pollack, an assistant professor and environmental and reproductive epidemiologist at George Mason University. However, because the survey was conducted at a single point in time, the researchers cannot determine which came first in the women's lives — giving birth or having shorter telomeres, Pollack said. It's also possible that for some yet-unknown reason, women with shorter telomeres are more likely than women with longer ones to have children, Pollack said.
More studies are needed that follow women over time and measure the length of their telomeres before, during and after pregnancy, she said.
"It would be interesting to see how telomere length changes during pregnancy, after birth and during the child-rearing years, and how these changes compare to women who do not have children," Pollack said.


1 analyzed 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的過去式和過去分詞 );分解;解釋;對…進行心理分析
  • The doctors analyzed the blood sample for anemia. 醫生們分析了貧血的血樣。 來自《簡明英漢詞典》
  • The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 這年輕人沒有分析自己蠱惑著迷的過程,因為對他來說,愛是個不可分析的迷。 來自《簡明英漢詞典》
2 genetic PgIxp     
  • It's very difficult to treat genetic diseases.遺傳性疾病治療起來很困難。
  • Each daughter cell can receive a full complement of the genetic information.每個子細胞可以收到遺傳信息的一個完全補償物。
3 chromosomes 11783d79c0016b60332bbf1856b3f77d     
n.染色體( chromosome的名詞復數 )
  • Chromosomes also determine the sex of animals. 染色體也決定動物的性別。 來自《簡明英漢詞典》
  • Each of four chromosomes divide longitudinally. 四種染色體的每一種都沿著縱向分裂。 來自《現代漢英綜合大詞典》
4 chronological 8Ofzi     
  • The paintings are exhibited in chronological sequence.這些畫是按創作的時間順序展出的。
  • Give me the dates in chronological order.把日期按年月順序給我。
5 pregnancy lPwxP     
  • Early pregnancy is often accompanied by nausea.懷孕早期常有惡心的現象。
  • Smoking during pregnancy increases the risk of miscarriage.懷孕期吸煙會增加流產的危險。
6 chronic BO9zl     
  • Famine differs from chronic malnutrition.饑荒不同于慢性營養不良。
  • Chronic poisoning may lead to death from inanition.慢性中毒也可能由虛弱導致死亡。
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