An international team of researchers has come to this remarkable conclusion after determining the biological age of women during and after pregnancy.
During the second part of pregnancy, the biological age of the pregnant women appeared to increase by approximately two years. But the biggest surprise came about three months after delivery, when the researchers re-determined the mothers’ biological ages, says researcher Kieran O’Donnell. “Three months after giving birth, we saw that the biological age had decreased remarkably. For some individuals even by eight years. So although pregnancy increases biological age, there is a clear and pronounced recovery postpartum.”
Biological age
O’Donnell and colleagues base that conclusion – published in the journal Cell Metabolism – as mentioned in a study among pregnant women. They looked at the biological age (see box) of the ladies at various times.
“We are all familiar with the concept of chronological age: our age in years, months and days that have passed since our birthday,” O’Donnell tells Scientias.nl. “Biological age, however, refers to the idea that the rate at which our organs, tissues and cells deteriorate can result in a biological age that is higher (or lower) than our chronological age.” A glance at your birth certificate is sufficient to determine your chronological age. But how can you determine your biological age? Scientists have already done quite a lot of research into this and various methods have been rolled out, O’Donnell says. “One of these revolves around DNA methylation, which is a chemical modification to the DNA that can change the functioning of that DNA. There are several places in the human genome where the degree of DNA methylation changes in a predictable way throughout life.” And by determining the degree of DNA methylation – and any deviations therein – in those places, you can also get an idea of someone’s biological age – and any deviations therein compared to the chronological age. And that is exactly what researchers did during and after the test subjects’ pregnancy. And so they discovered, among other things, that the degree of DNA methylation that women showed during pregnancy was more in line with the degree to which we would expect it if they were two years older than they actually were.
It became really surprising, as mentioned, when the researchers determined the biological age of the women three months after giving birth. Because around that time, aging seemed to have been reversed to some extent. For some women, the biological age after giving birth was even found to have decreased by eight years! Others, however, had to make do with smaller quantities. And what particularly struck the researchers was that the biological age of women who had a slightly higher BMI prior to their pregnancy decreased less sharply after pregnancy. Meanwhile, the biological age of women who breastfed after giving birth appeared to decrease very sharply postpartum.
Younger
An aging of two years during the second part of pregnancy. And a rejuvenation of eight years after childbirth. A quick calculation reveals that it tentatively hints that some women are biologically younger after pregnancy than they were before. But that’s not entirely certain; the researchers did not determine the biological age of the women prior to pregnancy. Follow-up research must therefore show how this develops over a longer period, including prior to and in the early stages of pregnancy.
Declaration
What also requires further research is the question of why the biological age of women increases during pregnancy and then decreases again. Based on this research, scientists can only guess at the answer to that question, O’Donnell says Scientias.nl. “A pregnancy is also seen as a natural ‘stress test’. Perhaps the physiological stress leads to changes that are ‘corrected’ in the postnatal period. Another, perhaps more challenging, idea is that during aging or when a system experiences stress, molecular changes occur that can be adaptive (and thus increase a cell’s chances of survival) or harmful. At this time we cannot determine whether the changes we see (in pregnant or recently given birth women, ed.) in the field of DNA methylation are adaptive or harmful, but it is tempting to speculate that pregnancy can result in adaptive molecular changes that are ‘corrected’ again in the postnatal period, when the system no longer experiences stress.”
More follow-up research
However, in addition to the issues mentioned above, there is much more that requires further research. “There is a lot to investigate further,” says O’Donnell. “First of all, we do not know whether the recovery (of biological age, ed.) that we see postpartum is relevant in the short and long term for the health outcomes of these women and whether these effects also accumulate during subsequent pregnancies. We also do not know whether the decrease in biological age that we see postpartum is simply because the system is recovering or – even more exciting – because the pregnancy simply has a rejuvenating effect at the bottom line.”
Such follow-up research is important, O’Donnell believes. “Our study reveals the remarkably dynamic biological changes that occur during pregnancy. The challenge now is to use that knowledge to improve the health and well-being of pregnant women.”
