Age is the single strongest predictor of miscarriage — but the full picture is kinder than the headlines suggest. In the largest study of its kind, covering 421,201 pregnancies in Norway and published by Magnus and colleagues in The BMJ in 2019, miscarriage risk was lowest at ages 25–29 (9.7%) and rose gradually through the early thirties before climbing more steeply after 35. Even at ages 40–44, where risk reaches 33.2%, about two in three recognized pregnancies do not end in miscarriage. Updated for 2026, this guide walks through the risk at every age, why the curve bends upward, and what the numbers actually mean for you.
A miscarriage is the loss of a pregnancy before 20 weeks. The figures below describe recognized pregnancies — pregnancies a woman knows about, usually after a positive test — so they reflect the odds you face from the moment you see those two lines. If you would like the short version for your own situation, our miscarriage risk calculator turns these age bands into a personal estimate.
Miscarriage Risk by Age: The Complete Table
Miscarriage risk follows a clear age pattern: it bottoms out at 9.7% in the late twenties, sits near 11% through the early thirties, and roughly doubles with each age band after 35. Here are the exact figures from Magnus et al. (BMJ, 2019):
| Maternal age | Miscarriage risk |
|---|---|
| Under 20 | 16.7% |
| 20–24 | 11.2% |
| 25–29 | 9.7% |
| 30–34 | 10.8% |
| 35–39 | 16.7% |
| 40–44 | 33.2% |
| 45 and over | 56.9% |
Across all ages combined, the average risk in the study was 12.8% — roughly 1 in 8 recognized pregnancies. Notice how flat the curve is between 25 and 34: the difference between age 27 (9.7%) and age 32 (10.8%) is barely one percentage point. The meaningful changes happen at the two ends of the reproductive years, not in the middle.
Why Does Miscarriage Risk Rise With Age?
The main reason is chromosomal. About 50% of early miscarriages involve a chromosomal abnormality — the embryo received the wrong number of chromosomes and could not develop normally. The medical term for a wrong chromosome count is aneuploidy, and aneuploidy becomes more common as eggs age.
A woman is born with all the eggs she will ever have, so a 40-year-old's eggs have been stored four decades longer than a 20-year-old's. Over that time, the cellular machinery that divides chromosomes during egg maturation makes more errors. The result is straightforward: the older the egg, the higher the chance the embryo it forms carries an extra or missing chromosome, and the higher the chance that pregnancy ends early. This is a biological lottery you did not cause and cannot diet, supplement, or exercise your way out of — which is also why most early losses happen even when a woman does everything "right."
The same chromosomal mechanism explains a second pattern: because conception itself gets harder as egg quality falls, it helps to look at the odds of getting pregnant and the odds of staying pregnant together. Our pregnancy chance calculator shows how conception odds shift with age alongside these loss rates.
The Curve Is J-Shaped, Not a Straight Climb
One finding that surprises most readers: miscarriage risk does not simply rise with age — it is J-shaped, meaning teenagers sit higher on the curve too. At under 20, the risk was 16.7% in the Norwegian data, exactly the same as the 35–39 band. Researchers attribute the teenage elevation partly to biology and partly to social and health factors that cluster in very young pregnancies.
The practical takeaway is about the shape of the climb on the older side. Risk stays near its floor until about age 34, begins a clear inflection around 35, and steepens noticeably after 38. The jump from the 35–39 band (16.7%) to the 40–44 band (33.2%) is the largest single step on the table — risk doubles across that boundary. That is why "35" gets so much attention in prenatal care: not because something switches off on a birthday, but because the slope genuinely changes there.
What the Numbers Mean at 35, 38 and 42
Percentages land differently when you translate them into real pregnancies. Here is what the same data looks like at three ages women ask about most.
At 35: About 1 in 6, and 5 in 6 Continue
At 35 you enter the 35–39 band, where miscarriage risk is 16.7% — roughly 1 pregnancy in 6. Framed the other way, about 5 in 6 recognized pregnancies at this age continue past the danger zone. Age 35 is also when many providers start offering extra screening, which can feel alarming, but the underlying odds are still firmly in your favor.
At 38: Still in the Same Band, Near Its Top
At 38 the risk is still described by the 35–39 band (16.7%), though you are closer to the top of it than a 35-year-old. The steepening after 38 means each additional year matters more now than it did at 31 or 32 — but a 38-year-old's odds remain far closer to the 35-year-old picture than to the 42-year-old one.
At 42: About 1 in 3, and 2 in 3 Continue
At 42 you are in the 40–44 band, where risk is 33.2% — roughly 1 in 3. That is a real increase, and it is honest to say so. It is equally honest to say that about 2 in 3 recognized pregnancies at 42 do not miscarry. Many women conceive at 42 and carry to term; the statistic describes a group average, not a verdict on any individual pregnancy.
Does a Previous Miscarriage Change Your Risk by Age?
Yes — a previous miscarriage raises the risk of another one, independently of age. In the same BMJ study, the age-adjusted odds ratio (a measure of how much the odds multiply after accounting for age) was 1.54 after one miscarriage, 2.21 after two, and 3.97 after three consecutive miscarriages.
Those multipliers sound frightening, but keep them in perspective. An odds ratio of 1.54 applied to a 30-year-old's baseline of about 10.8% does not mean a 54% chance of losing the next pregnancy — it points to a risk in the mid-teens, and the large majority of women with one previous miscarriage go on to have a healthy baby. Recurrence risk is also only half the story, because risk falls steeply with each passing week of a new pregnancy: our guide to miscarriage risk by week shows how quickly the odds improve, and the numbers change again once a heartbeat is seen, as explained in miscarriage odds after a heartbeat.
What About Miscarriage After IVF?
Age affects IVF pregnancies through the same chromosomal pathway, with one important twist: the age that matters most is the age of the egg, not the age of the woman carrying the pregnancy. A 42-year-old using donor eggs from a 28-year-old faces risks closer to the 25–29 band than to 33.2%. Preimplantation genetic testing (PGT-A) can also screen out many aneuploid embryos before transfer. The full picture, including how stimulation and embryo stage factor in, is covered in our guide to miscarriage after IVF — and if you have a transfer date, knowing how many weeks pregnant you are helps you place yourself on the risk curve.
The Reassuring Side of the Numbers
Read from the other direction, this table is mostly a story of pregnancies that continue. At 35–39, about 83% continue. At 40–44, about 67% continue. Even at 45 and over, where the risk of 56.9% is genuinely high, it is closer to a coin flip than a certainty — roughly 43% of recognized pregnancies in that group still carried on. Risk is real, but it is not destiny at any age on this table.
Two more context points help. First, paternal age plays a smaller role: some studies find an independent association once the father is over about 40–45, but it is modest next to the maternal-age effect. Second, age-based risk is a starting point, not the whole calculation — the week you have reached matters enormously, because most chromosomal losses happen early.
Putting Your Age Into Context
You cannot change the age of your eggs, and most early miscarriages are not preventable. What you can do is understand where you stand. Age gives you the baseline; the week of pregnancy refines it; a confirmed heartbeat refines it further. To combine those pieces for your own situation, estimate your personal odds by age and week with our calculator — and whatever number you see, remember it describes averages across hundreds of thousands of pregnancies. Your pregnancy is one story, not a statistic, and at every age on the table, that story has a real chance of a happy ending.