Surprising fertility effect on DNA
We always knew that having or not having a child has a huge effect on our bodies or the way we feel, but now we know fertility effect goes a lot deeper. Having a child changes our DNA. But how? in-fertility had a closer look to what childbirth does to us.
According to Science Alert and other media a new analysis of DNA collected from nearly 2,000 reproductive-age women in the United States reveals that those who had given birth showed evidence of altered genetic markers, the so called telomers, responsible for protection of DNA from effects of aging. In order to understand the telomers, you can try to imagine them as caps on the ends of the chromosomes, helping to protect the genetic information in the cells from deteriorating over time, in other words, protecting them from exposure to things that are harmful to our health.
The telomere length, which can be analysed from a simple urine test, could measure how much our bodies have aged on a cellular level and even how long left we have to live, new research suggests. Longer telomeres are considered better as shorter telomeres have been associated with cancer, heart disease and cognitive decline.
“We were surprised to find such a striking result,” epidemiologist Anna Pollack from George Mason University told New Scientist. Pollack and her team analysed data from from the period 1999–2002 from the National Health and Nutrition Examination Survey (NHANES) – a broad cross-sectional study charting the wellness of people in the United States over time. The survey included measurements of telomeres, when the scientists noticed something unusual. According to the findings childbirth had one of the most significant effects on the length of telomeres.
In the study, the team found that once they’d adjusted for things like age, ethnicity, education or smoking status, women who had given birth to at least one child had telomeres that were 4.2 percent shorter on average than those of women who had not borne children. This average meant an adjusted difference of 116 fewer base pairs in women who had given birth, which the researchers explain is equivalent to around 11 years of accelerated cellular ageing.
What’s amazing is that this telomere shortening associated with childbirth is even greater than what’s previously been observed in research examining the association seen with smoking (a cost of 4.6 years of cellular ageing) and obesity (8.8 years).
What’s more, in the study, the telomere shortening seemed to vary depending on how many children the women had delivered. “We found that women who had five or more children had even shorter telomeres compared to those who had none, and relatively shorter relative to those who had one, two, three or four, even,” Pollack told Newsweek.
It’s worth bearing in mind that due to the observational nature of the study, we can’t conclude a causation effect here, only a correlation. Naturally, speculations followed on what might have caused the negative effect, the stress, the health issues related to delivery, but all these are just speculations.
“We’re not saying ‘don’t have children’,” Pollack told New Scientist, and in-fertility believes that is the message to be remembered. However, many of us, facing problems to conceive and deciding for a family of two find this an important piece of information, motivating us to educate others and share what we learn #inthefertility.
The findings are reported in Human Reproduction.