生孩子真的會(huì)讓你“折壽”嗎？

如果說(shuō)養(yǎng)育孩子的艱辛是做母親必須付出的代價(jià)，還有一個(gè)代價(jià)是母親們不得不面對(duì)的，那就是老得更快。新研究發(fā)現(xiàn)，生過(guò)孩子的女性在生理上會(huì)比沒(méi)生過(guò)孩子的女性更老。生過(guò)孩子的女性DNA端粒更短，這意味著細(xì)胞壽命更短。

Women who give birth may be biologically "older" than women who don't, a new study suggests.

一項(xiàng)新研究發(fā)現(xiàn)，生過(guò)孩子的女性在生理上會(huì)比那些沒(méi)有生過(guò)的“更老”。

For the study, the researchers analyzed 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.

在該研究中，研究人員們分析了20-44歲之間的1556名美國(guó)女性信息，她們參加了1999年至2002年期間的全國(guó)調(diào)查，并給出了血液樣本。

The researchers looked at the genetic material inside the women's cells, specifically the length of their telomeres. These are caps on the ends of chromosomes 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 chronological age.

研究人員們觀察了這些女性細(xì)胞內(nèi)的遺傳物質(zhì)，尤其是她們端粒的長(zhǎng)度。這些位于染色體末端的小帽子能夠保護(hù)染色體不受損。人們?cè)谧兝系倪^(guò)程中，端粒也會(huì)自然縮短，但這個(gè)結(jié)構(gòu)在每個(gè)人身上變短的速度均不同。一個(gè)人的端粒越長(zhǎng)，他們的細(xì)胞理論上能夠分裂的次數(shù)就越多。并且，端粒也被科學(xué)家們視為生理年齡的標(biāo)記，即一個(gè)人的細(xì)胞年齡，而不是他們的實(shí)際年齡。

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.

在研究中，至少生過(guò)一個(gè)孩子的女性端粒長(zhǎng)度平均比那些未生產(chǎn)過(guò)的女性短百分之四。即便研究人員們考慮了其它能影響端粒長(zhǎng)度的因素(比如她們的實(shí)際年齡、身體質(zhì)量指數(shù)和吸煙習(xí)慣)，這些發(fā)現(xiàn)依舊站得住腳。

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.

這些發(fā)現(xiàn)表明生產(chǎn)史可能與更短的端粒之間存在著聯(lián)系。該研究的概述在美國(guó)公共衛(wèi)生協(xié)會(huì)于丹佛市舉辦的會(huì)議上發(fā)布。

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.

該研究并未探究這一聯(lián)系背后的原因，但有猜測(cè)認(rèn)為生孩子會(huì)增加女性的壓力，而高壓與更短的端粒有關(guān)。

"It is possible that pregnancy, birth and child-rearing can induce chronic 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.

美國(guó)喬治梅森大學(xué)的助教、生態(tài)環(huán)境與生殖流行病學(xué)家安娜•波萊克參與了該研究，她表示：“有可能懷孕、生產(chǎn)和撫養(yǎng)孩子帶來(lái)了慢性壓力，并通過(guò)炎癥通路縮短了端粒長(zhǎng)度。”然而，由于調(diào)查是在某個(gè)時(shí)間點(diǎn)開(kāi)展的，研究人員們無(wú)法確定生孩子與更短的端粒長(zhǎng)度之間，哪一個(gè)先出現(xiàn)。波萊克說(shuō)，有可能出于某些未知的原因，端粒更短的女性比端粒更長(zhǎng)的女性更有可能生孩子。

More studies are needed that follow women over time and measure the length of their telomeres before, during and after pregnancy, she said.

她說(shuō)，還需要進(jìn)一步的追蹤研究來(lái)確定女性的端粒在生孩子之前、懷孕期間和產(chǎn)后的長(zhǎng)度。

"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.

波萊克說(shuō)：“觀察端粒長(zhǎng)度在孕期、產(chǎn)后和養(yǎng)育孩子過(guò)程中的變化，并將其與沒(méi)有生過(guò)孩子的女性比較是一件非常有趣的事情。”