Decline in fertility after age 30 may be vastly overstated

As a woman, you do become less fertile as you get older, eventually culminating in menopause and the end of your potential babymaking years. But what does "less fertile" mean, and at what age, and how quickly does the drop-off in fertility happen?

According to this really fascinating piece by Jean Twenge at The Atlantic, some of the commonly cited scare stats — that one in three women ages 35 to 39 will not be pregnant after a year of trying, say — are based on extremely old data collected from historical birth records that don't necessarily reflect what's happening with real women who are alive right now. That statistic mentioned above, for instance, comes from French records (likely those collected by local church baptismal registries) for the years 1670 to 1830.

That matters because fertility is affected by things like quality of nutrition, infection rates, and even childhood illnesses — all of which have changed drastically for the average Western woman since the 19th century.

Look at more modern records, and the outlook for post-30 babymaking is completely different.

Surprisingly few well-designed studies of female age and natural fertility include women born in the 20th century—but those that do tend to paint a more optimistic picture. One study, published in Obstetrics & Gynecology in 2004 and headed by David Dunson (now of Duke University), examined the chances of pregnancy among 770 European women. It found that with sex at least twice a week, 82 percent of 35-to-39-year-old women conceive within a year, compared with 86 percent of 27-to-34-year-olds. (The fertility of women in their late 20s and early 30s was almost identical—news in and of itself.) Another study, released this March in Fertility and Sterility and led by Kenneth Rothman of Boston University, followed 2,820 Danish women as they tried to get pregnant. Among women having sex during their fertile times, 78 percent of 35-to-40-year-olds got pregnant within a year, compared with 84 percent of 20-to-34-year-olds. A study headed by Anne Steiner, an associate professor at the University of North Carolina School of Medicine, the results of which were presented in June, found that among 38- and 39-year-olds who had been pregnant before, 80 percent of white women of normal weight got pregnant naturally within six months (although that percentage was lower among other races and among the overweight). “In our data, we’re not seeing huge drops until age 40,” she told me.

Read the full story by Jean Twenge at The Atlantic

Image: Baby Emily, a Creative Commons Attribution No-Derivative-Works (2.0) image from kittwalker's photostream


  1. My one caution is that there is a tendency to think only about the immediate circumstances which will result in a newborn baby.  Prospective parents need to understand that it’s a 20+ year commitment.  Just because you *can* give birth in your 40’s doesn’t necessarily mean you’ll be healthy and energetic enough to deal with teenagers in your 60’s.  You’re also putting your grandchildren at slightly greater risk since they are less likely to have functioning grandparents for the whole of their childhood (yes, there are studies on that!).

    I know over a dozen children at my kids’ schools who lost a parent before they were in high school due to medical issues.  We’re talking about diseases that struck in their 50s, 60s and 70s….and they left behind young children.  Don’t assume you’re going to be spry (or even alive) at 70 when you make the calculations on when to have children.

      1. If you have kids when you’re young then someone will bemoan “having children before you’re emotionally or financially prepared.” If you have kids when you’re older then someone will bemoan “having kids too late in life to keep up with them through their adolescence.” It’s one of those damned-if-you-do, damned-if-you-don’t things.

        1. Parenting: the only job in human existence where everyone around you is better qualified for it, and every last one of them feels obligated to explain why.

          1. And let’s not forget: 

            If you opt to have children, you’re being selfish for contributing to humanity’s ever-growing destruction of the planet just to satisfy some ego thing.

            If you opt not to have children, you’re being selfish for spending your whole life focusing on your own desires instead of helping raise the next generation of humanity.

          2.  well, yeah, except that my one child will turn out to be the person that solves global warming and future energy supplies and all pollution, and will provide a pony for everyone, so i figure i get a free pass.

          3. @PaulDavisTheFirst:disqus : The important thing to remember is “my personal reproductive decisions are correct, but your personal reproductive decisions are just irresponsible.”

          4.  This is where Idiocracy comes into play. . .

            #1 applies to stupid people.

            #2 applies to smart people.

    1. Studies on functioning grandparents? My grandparents lived on opposite sides of the country when I grew up. What sorts of horrible effects do I suffer now as an adult that I can blame on this fact?

    2. I had a couple of classmates whose fathers had been 70ish when they were born. One of them died when my friend was a toddler. The other one was still alive and could regale you with tales of life in Serbia in the 19th Century. It was pretty unusual back in the 1960s, but now it seems a lot more common.

  2. I thought the main reason we talk about the clock ticking is because of the increased chance of birth defects and pregnancy complications as we age. Are those vastly overstated too? Cause if not this doesn’t really change my outlook on the whole thing.

    1. To some degree yes. My wife and I (in our late 30s) were told with our first that the hyperbole surrounding women in her age group is becoming less relevant. One rating system categorized her as “elderly” while another said she was in the middle of her fertility spectrum.

      1. I conceived at 35 and went through the additional genetic screening only to find that my risk was equal to that of someone in their late 20’s.  Best of all, on the back of the paperwork was scrawled “geriatric”.  Not at all offensive. /s

      1.  That’s how some species of albatross do it. Each pair lays two eggs every season. The eggs hatch a few days apart. The older chick then proceeds to kill the younger one. But if the older has a developmental problem, the younger kills the older.

        It worked just like this in my family. My parents have no idea what happened to my older brother. Of course, it’s a bit different because he wasn’t disabled or anything. I just didn’t like him very much.

  3. chgoliz — What you say is true, of course, but young parents die as well.  And young parents can fall ill and be unable to be “healthy and energetic” enough to raise their children.  There’s no guarantees in life.  (And pre-birth control, women had children until menopause — the only difference being that kids with older parents then were the tail end of large families, not the product of an intentionally smaller one.)

    I have what I call two only children.  I had my son when I was 25 and my daughter when I was 40.  (Two marriages.)   And I am a very different mother to each (in some ways — my core values of love and respect haven’t changed.)  I had more energy when I had my son but I have more patience and experience (and money) for my daughter.  There are always trade-offs.  If a child is loved and can be cared for, neither age nor resources should be the deciding factor.

  4. I’d advise anyone who’s looking at having kids past 30 to at least get checked out (man and woman!). If you’re that one person who’s on the far end of the bell curve and going infertile early, the statistics and such will be cold comfort. Worst case you pay for a couple unnecessary tests and know for sure.

  5. Too many people (by which I mean women) aren’t thinking in terms of having a stable relationship locked in by say age 32 so they are situated to try to conceive at age 35.  39 and looking for a husband is too late. It might take 5 years to find a husband.  In many cases it has less to do with the age of fertility, and more to do with badly underestimating the amount of prep work needed.

    Call me old fashioned, but I put no stock in the idea of someone  simply finding a sperm donor and winging it as a middle aged single mother with no idea of what it’s like to be up all night for months with a colicy baby. There’s no dating, no social life, and no money to spare.  And the single parent is on a terrifying high wire of financial insecurity. Want to have a kid and no medical insurance? Want to live in your car? And your parents have died or  retired to a tiny condo with no resources to help you in any way?  Want to be the 60 year old single mother of teenager? Want to be the 60 year old single mother of teenager with autism who will never really be independent?

    1. Too many people (by which I mean women) aren’t thinking…

      That kind of sums up the whole comment, really.

      1. Unless single men are now worrying about the age of their eggs, your comment may reveal more about your own knee jerk sexism.

        1.  I think he was referring to your knee-jerk sexism, but maybe I’m projecting.

          1. If someone wants to offer an actual  response instead of ad hominems, have at it. 

            Does tossing ad homs to get on-line high-fives indicate someone is mature enough to know anything about parenthood? 

          2. “Won’t somebody please think about the stupid, stupid wimmenz” is what your comment boils down to.  Did you really think no one was going to call you on it?  If that’s not what you meant to imply, take this as an opportunity to clarify your statement rather than go on the defensive.

          3. Once those ladyparts kick into overdrive, the brain just shuts down. Everybody knows that. Why do you think that they call it ‘hysteria’?

          4. No, but in the last couple of years BB comments (and certain commenters) have a tendency to jump on the sexist, racist, privilege, ect.. bandwagon.

            Frankly I’m not really sure how a man decides to have a child as an only father (outside of adoption I suppose).  As far as your original post goes, I’m in my mid 30’s and I only know a few single mothers.  Most of them from what I know didn’t choose to have their children when they did.  But the flip side of that is most of them had their kids while they were in their early to mid twenties.  So while it wasn’t the best of times their families were still around to help out.

          5. Frankly I’m not really sure how a man decides to have a child as an only father (outside of adoption I suppose).

            Surrogacy? Ricky Martin. Clay Aiken. Elton John. Neil Patrick Harris.

          1. Ever watch movies?
            Ever notice how it seems completely realistic and natural that an unmarried/unattached woman in her late 30’s/early 40’s wants to have a child?  That they spend the vast majority of the movie trying to get/have that child.  And by the end of it, assuming a child is conceived, everything works out and they live a happy and wonderful life?

            -Ever notice how it’s rare that people actually have responsibilities or jobs in movies?
            -Money and time just seem to grow on trees.
            -And since you have all the resources in the world child rearing is super easy and somewhat comical?

            And I fail to see how the Parental Age Effect makes any difference on the desire of a person to have a child when they aren’t in a relationship.  It certainly affects the odds and risks associated with having one, but not the desire to do it.

            You are right it’s not fair to place all the reproductive responsibilities on the woman, well unless that woman is the only person involved – then who else can you place it on?

          2. I’m not sure where you’re going with that line of thought. In any case I wouldn’t recommend looking to Hollywood movies as a realistic model for how to live one’s life.

            How about we all just butt out of each other’s reproductive choices entirely, especially when the science may not support our opinions anyway?

          3. What does REAL LIFE have to do with FICTIONAL MOVIES?!


            I don’t even, man.  I don’t even.

        1. Call me old fashioned, but I put no stock in the idea of someone  simply finding a sperm donor and winging it as a middle aged single mother with no idea of what it’s like to be up all night for months with a colicy baby. 

          If people aren’t actually doing this (aside from one or two rare cases, which you can find for just about anything) than your deep concern about women’s choices is kind of misplaced and unnecessary, wouldn’t you say? 

          1. Are you agreeing, disagreeing, hyperventilating, or what?  

            So far you got something that sounds vaguely like an accusation except for not actually making a point.

          2. I met my wife at 39 and married her at 40.  We had our daughter at 42.  It seems to be working out fine for all of us. I think your initial comment is reductionist, and I disagree with it.

          3. >>I met my wife at 39 
            I’m glad you are all doing well.  I think it would “reductionist” to extrapolate your individual experience to other  people.

          4. why would you bother to mention an idea, and to remark that you put no stock in it, if you do not believe that people are actually doing (or at least talking about doing) that?

          5. Preston, 
            If you can’t be polite to people (and especially if you can’t stop accusing women who point out flaws in your logic as “hyperventilating”) I am going to ban you.  Fair warning. 

            Here’s what I mean: you are declaring women to be irresponsible for not getting married when you think they should get married and you are expressing deep concern that their only alternative to getting married when you think they should get married is to become intentional single mothers with the help of a sperm bank. 

            You have provided zero evidence that this scenario is actually playing out. 

            Thus, you being deeply concerned about it is a lot like me being deeply concerned men are being irresponsible when they choose to forego marriage to a human and, instead, wed giant anime body pillows. I can find some examples of this happening, sure. But if it’s not actually something that’s a real trend, then there’s not a lot of point in me hand-wringing about what it’s going to do to children, “men” as some giant homogenous group, or the future of the human race. 

          6. I think any discussion of parenthood is effectively over when threats are made, so I’m out.

    2. “Want to have a kid and no medical insurance?” 

      Oh, please trust there are many, many, many two-partner family households today, yesterday, and tomorrow, with absolutely no medical insurance.

      And be reassured that being with my boyfriend, and thus in a traditional heterosexual two-partner relationship, has not given me (or him, really) any more idea of what colicky babies are like (except loud and annoying), or what colic is.   

      1. Children don’t need medical insurance?  

        Well that certainly took an unexpected turn!

        1. How do you get that?  Its a fact.  Not a statement of preference.  Ah but you are a troll who intentionally “misunderstands” the responses provided to your flip and thoughtless comments.

    3. What is this comment saying?  I don’t even…

      Is your point that women should stop messing around and start looking for a husband by 32?  Because believe me friend, I don’t think it’s for lack of trying…

      1. Since apparently the rest of the group is somehow lacking in clarification skills today I’ll distill it for you:

        -Society in general (along with a healthy dose of Hollywood) has pushed this notion that women can have it all.  They can be a career woman dedicated to their jobs and when they are ready find Mr. Right and have a family no problems.  Reality is much much different.  There isn’t anything wrong with wanting to make it big and dedicating as much time as you need to achieve that.  But there has to be some understanding that you’ll (potentially) be giving up something to make that happen.  (The same applies for men, but in a slightly different way.)

        So in a way, yes she is saying that.  But she is also saying women (and men) need to be realistic about relationships and children.  You can’t just walk into a store and pick them up.

        1. The same applies for men, but in a slightly different way.

          Yeah, reality deforms itself to accommodate men doing it, while treating women like sociopaths for trying to do the same thing.

          1. I’ll grant you it may be easier for a man to find a woman who would be willing to basically raise their/his children for him (or do like a career woman might hire a full time nanny), either way being married to a person who devotes more time to their career than their spouse/children isn’t what most people desire for themselves or their children.

  6. Teh wimmenz need to be married to husband young, to start providing him with male offspring. Is in the bibble — read your bibble! The USA is a christina nation no matter what your harverd educated snobbs say!

  7. It’s too bad that the “discussion” of parenting here has somewhat obscured that fact that there’s some interesting science in this post.  When researching this subject a few years ago, I was surprised at how sharply fertility seemed to decline in a woman’s late 30’s.  Given the size of the population and general diversity of people, it seemed counter-intuitive to me that there would be such a sudden drop-off. I’m reassured to learn that these statistics are based on a poor sampling.

  8. I’m 31, and my mother just turned 74. And let’s not talk about my dad, who turns 86 in september.

  9. Interesting how my simple caution to think ahead about the long term aspects of parenting instead of just focusing on “we’re finally getting a baby!” got a lot of responses that proved my point.

    It worked out for me, even young parents die, etc….those are justifications for one’s personal choice.

    Here’s a question to follow up:  how many of you have written legal documentation detailing what happens to your children if something happens to their parents?  Not a general sense that an extended family member would take them in….actual documents which would hold up in family court.  And how many of you had that in place BEFORE your first child was born?

    That’s the kind of long term thinking I’m talking about.

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