URGENT DISCLAIMER: I have never been pregnant, so I have no personal experience with any of the real life side effects of pregnancy. I am in awe of those of you who do. Several of my brave friends have shared a few choice tidbits, which is how I know that pregnancy is not for the faint of heart. Well, that and a lot of science.
Anyway, the reason for this post is a recently published study in which the authors have boldly declared that pregnancy does in fact accelerate the aging process. This is what they’ve titled their study:
Reproduction predicts shorter telomeres and epigenetic age acceleration among young adult women
I can already hear my friends – of course pregnancy accelerates aging! Because it ends in children, and children give their parents gray hair and heart disease. They’re always finding that one outlet you forgot to cover, mouth kissing the dog, and discovering their acrobatic skills on the second story balcony, precariously balancing twelve feet from the concrete floor that now seems like more of a health hazard than a “sleek feature for the modern homebuyer.”
And also, our mothers have been loudly beating this concept into our brains pretty much since birth.
But science says (1) your mom was right (Take a moment to get your arms around that. If you’re struggling, remember that no one can make you tell your mom that she was right.), and (2) babies actually do even more to steal away their mothers’ youth*.
How exactly do they accomplish this? Well, first, take heart. Your baby isn’t using it’s tiny fingers to damage your DNA. Technically, your body is doing that. The biochemical processes involved in pregnancy shorten the ends of your chromosomes and they alter a process involved in DNA traffic management*, both of which contribute to aging at the cellular and molecular levels.
Telomeres Keep Your DNA Young
Your genetic material hangs out in chromosomes, the three-dimensional DNA sculptures found in the nucleus of each and every one of your cells. Every time a cell replicates, and most of the cells in your body do that pretty frequently, it copies that DNA and passes it on to the new cell. For the process to go off without a hitch, the cell uses a complicated system that I’m going to grossly oversimplify and probably offend any molecular biologist who stumbles upon this post. But, if you’re not a scientist, you’ll get the take-home message. And that’s why I’m here.
Imagine that your chromosome is just a straight line, not a complicated three dimensional shape. At the end of that straight line is a little tail that we call a telomere. The telomere exists to make sure that your DNA is copied completely and faithfully, so that you don’t lose any important information toward the end of your DNA strand. The DNA copying process looks kind of like this:
It takes TONS of cycles (yes, that is the technical scientific term for it) of cell division for telomeres to get short enough to cause real problems in your cells. But, when that happens, the problems are very real. The cell with the short, sad telomeres (or none at all) will enter a phase called senescence, which basically means that the cell stops working correctly and may die.
Fortunately for most of us, our bodies make this cool enzyme that adds pieces back to our telomeres after they’ve been lost. Kind of like when you lose your favorite t-shirt. You think you’ll never see it again, but then it turns out your mom just sewed the sleeve back on for you, and you get another 15 years with it.
So, what does that have to do with pregnancy and aging?
Pregnancy Shortens Telomeres*
Yep, this study investigated a group of women, average age 27 years old, who had experienced varying numbers of pregnancies. Here’s the breakdown:
0 Pregnancies | 507 Women
1 Pregnancy | 174 Women
2 Pregnancies | 102 Women
3 Pregnancies | 28 Women
4 Pregnancies | 7 Women
When they analyzed the effects of pregnancy on telomere length, they found that each additional pregnancy generated between 0.34 and 3.67 years worth of telomere aging. This finding was determined after controlling for other variables like age. So it wasn’t just that older women were more likely to have been alive long enough to have three pregnancies. There was a real, statistical shortening in telomere length as a result of additional pregnancy.
These researchers found something else kind of interesting. Additional pregnancies don’t seem to affect future fertility.
So even though each pregnancy ages mom’s cells, it doesn’t seem to affect her ability to inflict that damage on herself again with another pregnancy.
Pregnancy Changes Your DNA*
This study also investigated the effects of pregnancy on something called DNA methylation, which the video below hilariously explains.
Basically, methylation alters the parts of your DNA that can be expressed. It doesn’t add or subtract information, it just hides or shows it. Kind of like when you’re supposed to be reading your history book but you’ve put Harry Potter inside your history book. You’re not learning history, but the information is still there for when you’ve had enough Hogwarts for the day. I know there’s no such thing. Just use your imagination.
Back to this methylation issue.
Your cells run into a lot of problems when methylation gets in the way of their normal functions.
The researchers in this study assessed what they call DNA-methylation age, and it turns out pregnancy affects that too*. Each additional pregnancy in the study increased DNA-methylation age by between 0.29 and 0.63 years.
What Does It Mean?
Don’t start blaming your children for the fact that you can never find your sunglasses just yet. Unless they’re relentless little kleptos, in which case, please carry on as usual.
For the rest of you, as is often true in science, one study is not definitive on its own. At least not for the whole population.
Another study from 2017 looked at the same basic concepts, and you know what they found? Something completely different.
The CARDIA Study actually began in 1985 and has been conducted exclusively in the United States. At the 20 year follow-up point, 72% of the original 5115 subjects were still reporting their data, which is kind of amazing in and of itself. #GeekMoment
More interesting to me is the fact that this study found no relationship between number of pregnancies and telomere associated aging.
Note: The study at the beginning of this post was done in the Phillipines.
Given the conflicting information between these two very different populations of women, I’d venture to say that pregnancy does age your cells. If you happen to live in the Phillippines and possibly other places in which the conditions of pregnancy create the same cellular conditions.
No Really, What Does It Mean?
Well, we know women in the Philippines experience aging at a genetic level during pregnancy, adding years to the state of their genetic code. We also know that the same isn’t true for women in the United States.
So what’s the moral of this story? If you’re going to have a baby, and you’re choosing between pregnancy in the US or in the Phillippines, choose the US.
It’s science, y’all!
*All starred statements only apply to the subjects of the Philippines study.
Also, scientist gripe: that study title was all kinds of wrong. For science. Here’s an appropriate modification:
Reproduction predicts shorter telomeres and epigenetic age acceleration among young adult women IN THE PHILIPPINES