Miscarriage is common: about 15 in 100 recognised pregnancies end in one, according to pooled data published in The Lancet in 2021. Here we set out the key figures on chromosomes, age and recurrent miscarriage, where each one comes from, and why different sources quote different numbers.
Statistics describe large groups of people, not your pregnancy. If you would like to understand what the numbers mean for you, our genetic counsellors can go through them with you by video.
At a glance
Each figure is explained further down, with its source. Where good studies disagree, we show the range.
Frequency
A miscarriage is the loss of a pregnancy before 24 weeks. The NHS calls a loss before 14 weeks an early miscarriage and one from 14 to 23 weeks a late miscarriage. NICE Clinical Knowledge Summaries (CKS) estimate that about 8 in 10 miscarriages occur in the first trimester.
A 2021 review in The Lancet pooled studies from several countries and found that about 15 in 100 recognised pregnancies end in miscarriage, roughly 1 in 7. An older patient leaflet from the Royal College of Obstetricians and Gynaecologists (RCOG, 2016) puts it at up to 1 in 5 during the first three months, and NICE CKS quotes a range of 8 to 24 in 100. Worldwide, the Lancet authors estimate around 23 million miscarriages a year.
Counted per person rather than per pregnancy, the figure is larger: NICE CKS estimates that about 1 in 4 women will have a miscarriage in their lifetime, partly because many women are pregnant more than once. The true total is probably higher still, because some losses happen before a pregnancy is recognised and are never counted (NICE CKS; Magnus et al., BMJ 2019).
Chromosomes
Chromosome abnormalities in the pregnancy are the most common known cause of miscarriage. The RCOG puts the figure at about 1 in 2 miscarriages. The Lancet review found them in 60 in 100 samples of miscarriage tissue, compared with fewer than 1 in 100 babies born when there has been no prenatal testing. NICE CKS quotes a wider range: 50 to 85 in 100 tissue samples tested after a first-trimester miscarriage.
Where a study lands depends partly on the test. Traditional chromosome analysis (karyotyping) needs living cells to grow, and the RCOG's 2023 guideline reports that this fails in about 1 in 5 samples. Microarrays, newer whole-genome tests, do not need living cells and, according to the same guideline, can find tiny missing or extra sections of chromosome in a further 5 to 7 in 100 miscarriages, although not every such finding explains the loss.
History matters too. European guidance (ESHRE, 2022) cites a review finding chromosome changes in about 45 in 100 single miscarriages and a broadly similar 39 in 100 later miscarriages in people with recurrent miscarriage, while NICE CKS notes that the share tends to fall as the number of previous losses rises. The kinds of change are explained in chromosomal causes of miscarriage.
Age
The Lancet review names a woman's age and her number of previous miscarriages as the most prominent risk factors. The age effect comes mainly from the egg: with age, the number and quality of the remaining eggs decline, and chromosome errors such as trisomies (an extra copy of one chromosome) become more common (RCOG; NICE CKS).
The Lancet authors describe the chance of trisomy 16, the most common chromosome change in miscarriage, rising steadily from age 20 to 40, while most other trisomies rise more sharply from around 35. A partner's age matters less: the NHS lists the baby's father being 45 or over as a risk factor, and NICE CKS notes that this effect is smaller than that of the mother's age.
Age raises the odds without deciding the outcome. In the pooled Lancet figures, about 63 in 100 pregnancies at 40 to 44 did not end in miscarriage; the older Danish figures used by the RCOG put it nearer half. The table below shows both data sets, with a third from Norway.
The figures
Miscarriages per 100 recognised pregnancies. Each column is a separate study, so compare down a column rather than mixing figures across columns.
| Age | Denmark 1978–92 (figures in the RCOG leaflet) | Pooled studies (Lancet, 2021) | Norway 2009–13 (BMJ, 2019) |
|---|---|---|---|
| Under 20 | 13 in 100 | 16 in 100 | 16 in 100 |
| 20 to 24 | 11 in 100 | 12 in 100 | 11 in 100 |
| 25 to 29 | 12 in 100 | 12 in 100 | 10 in 100 |
| 30 to 34 | 15 in 100 | 14 in 100 | 11 in 100 |
| 35 to 39 | 25 in 100 | 18 in 100 | 17 in 100 |
| 40 to 44 | 51 in 100 | 37 in 100 | 32 in 100 |
| 45 and over | 93 in 100 | 65 in 100 | 54 in 100 |
Denmark: Nybo Andersen et al., BMJ 2000. The study counted only miscarriages treated in hospital; its main estimates were about 9 in 100 for ages 20 to 24 and 75 in 100 for 45 and over. The figures shown, which the RCOG leaflet uses, come from the authors' extra calculation assuming only 8 in 10 miscarriages reached hospital, so the 45-and-over figure in particular is an upper estimate. Its youngest group was 12 to 19. The RCOG leaflet groups the under-35 rows as 11 to 15 in 100.
Lancet: Quenby et al., 2021, Table 3. The 45-and-over figure rests on fewer than 2,000 pregnancies, with a margin of error of about 50 to 85 in 100.
Norway: Magnus et al., BMJ 2019; 421,201 pregnancies, corrected for induced abortion.
Making sense of it
The differences do not mean that one study is wrong: each counted miscarriages in its own way. The two newer data sets are broadly similar, and the RCOG leaflet figures sit at the upper end of the range, partly because of the hospital allowance described below. No column can give your personal chance, which is something a genetic counselling appointment can help with.
The Danish study included only miscarriages admitted to hospital; the RCOG figures add an allowance assuming 1 in 5 never got that far. The Norwegian study linked national birth, patient and abortion registers.
Some pregnancies end in termination before a miscarriage could happen. Correcting for this modestly lowered the Norwegian figures for the youngest and oldest women (Magnus et al., 2019).
The Danish data cover 1978 to 1992 and the Norwegian data 2009 to 2013, while the Lancet review pools studies from several countries.
Far fewer people are pregnant in their mid-40s, so the oldest groups are small (about 1,300 pregnancies in the Norwegian study) and their estimates vary the most.
Recurrent miscarriage
In the UK, recurrent miscarriage means three or more early miscarriages, which do not have to be one after another (RCOG). The RCOG's 2023 guideline allows investigations to start after two losses if a doctor suspects a cause, and European guidance (ESHRE, 2022) defines recurrent pregnancy loss as two or more losses.
The RCOG estimates that about 1 in 100 women have recurrent miscarriage. The Lancet review gives about 2 in 100 women with two miscarriages and about 7 in 1,000 with three or more. NICE CKS reports that antiphospholipid syndrome (APS), an immune condition affecting blood clotting, is found in about 15 in 100 people with recurrent miscarriage, and that no cause is found in about half of couples.
Occasionally one partner carries a balanced chromosome rearrangement: all their chromosome material is present but arranged differently. It does not affect their health, but a pregnancy may receive an unbalanced form of it. This affects around 3 to 6 in 100 couples with recurrent miscarriage: 3 to 5 in 100 according to NICE CKS, and 6 in 100 after three miscarriages according to the RCOG. See parental karyotype after miscarriage.
Previous losses
Pooled figures from the Lancet review (Quenby et al., 2021, Table 3). Age and previous losses each raise the risk independently (Lancet 2021; Magnus et al., 2019), so these averages will be higher for some people and lower for others.
| Previous miscarriages | Next pregnancy ends in miscarriage | Next pregnancy does not end in miscarriage |
|---|---|---|
| None | About 11 in 100 | About 89 in 100 |
| One | About 20 in 100 | About 80 in 100 |
| Two | About 28 in 100 | About 72 in 100 |
| Three or more | About 42 in 100 | About 58 in 100 |
The right-hand column is simply the remainder of each 100; it is not quite the same as a live birth rate.
Looking ahead
Most people who miscarry go on to have a baby. After a single miscarriage, about 8 in 10 next pregnancies in the Lancet figures did not end in miscarriage. Even after recurrent miscarriage with no cause found, NICE CKS reports that up to 3 in 4 couples have a live birth in a future pregnancy with supportive care and emotional support in a dedicated early pregnancy unit.
Age and history shape those chances. In a Danish study of women referred to a specialist recurrent miscarriage centre, quoted in the ESHRE guideline, about 8 in 10 aged 20 to 24 had a baby within five years, compared with about 4 in 10 aged 40 or over; about 2 in 3 did overall.
The cause matters as well. The RCOG's 2023 guideline says that when testing shows a chromosomal cause, the outlook for the next pregnancy is better than when the chromosomes were normal, once age is allowed for, unless a parent carries a rearrangement.
Even for carrier couples the long-term picture is encouraging. In a Dutch study of couples with two or more miscarriages, 83 in 100 carrier couples had at least one healthy child over about six years of follow-up, close to the 84 in 100 of non-carriers, although carriers had more miscarriages along the way (Franssen et al., BMJ 2006). See pregnancy after a chromosomal miscarriage.
Reading the numbers
Miscarriage figures are everywhere online and rarely come with context. These questions help you judge what a number really tells you.
Per pregnancy or per person? About 15 in 100 recognised pregnancies end in miscarriage, yet about 1 in 4 women miscarry in their lifetime. Both are right.
Which pregnancies were counted? Very early losses are often missed, so published rates are probably underestimates.
When and where? Danish figures from 1978 to 1992 and Norwegian figures from 2009 to 2013 can legitimately differ.
A link or a cause? The Lancet authors stress that an association does not prove a factor caused a miscarriage.
A group or you? An average cannot say what happened in one pregnancy; only testing the pregnancy can show a chromosomal cause.
NHS care
For bleeding or pain in early pregnancy, the NHS advises contacting your maternity unit, an early pregnancy unit if you are under 20 weeks, or NHS 111, and calling 999 if the bleeding is heavy or the pain severe.
Routine NHS investigations usually start after three miscarriages, or after one second-trimester loss. The RCOG's 2023 guideline recommends chromosome testing of pregnancy tissue from the third miscarriage, tests for APS and thyroid function, and a scan of the womb, ideally 3D. Parents' chromosomes are checked only if the tissue shows an unbalanced rearrangement or could not be tested. If no cause is found, it recommends supportive care, ideally in a dedicated clinic.
After one or two early miscarriages, NHS investigations are not usually offered unless a cause is suspected, so some people look for answers privately, alongside their NHS care.
London Pregnancy Clinic
We are a private clinic in the City of London and West London; genetic counselling is online, so you can join from anywhere. These services help if you want to understand your own chances rather than the averages.
Online, by video
Talk through your history, any results and the figures that apply to you with a registered genetic counsellor, through our partner Jeen Health. A 60-minute appointment (£140) suits more complex histories.
After repeated losses
A consultant gynaecologist consultation and pelvic scan, with blood tests including lupus anticoagulant and anticardiolipin antibodies (APS markers) and a thyroid profile. Book with a £300 deposit, deducted from the total.
When it is indicated
A blood test of one or both partners' chromosomes, arranged with Jeen Health, when pregnancy tissue shows an unbalanced rearrangement or could not be tested. £290 for one person, £550 for a couple.
Doctor-led genetics
For complex results, a known rearrangement in the family, or detailed planning before another pregnancy, with Dr Harry Leitch, Consultant in Clinical Genetics. Enquire to book.
No. NICE CKS notes that 'advanced maternal age' usually means 35 or older, but in Norwegian national data the risk began rising after 30 and kept climbing, rather than jumping at one fixed age (Magnus et al., BMJ 2019). At 35 to 39, newer data give about 17 to 18 in 100, and the older Danish figures used by the RCOG about 25 in 100.
Possibly, but a statistic cannot tell you. A figure like 1 in 2 describes a large group. Only testing the pregnancy itself can show whether a chromosome change was present, and a normal result does not rule out other causes. What can I test now? explains which options may still be open to you.
In the pooled Lancet figures, about 28 in 100 pregnancies in women with two previous miscarriages ended in miscarriage, so about 72 in 100 did not; your age and history shift this. The RCOG says investigations can begin after two losses if a cause is suspected. Our recurrent miscarriage page explains the tests and our consultant-led package.
Mostly not. Studies generally count pregnancies that were recognised and recorded, so very early losses are often missed, and NICE CKS says the true rate is probably higher than published figures. Read more about chemical pregnancy.
Nobody knows exactly. NICE CKS reports over 50,000 UK hospital admissions a year for early pregnancy loss, but many miscarriages are managed at home, and the Lancet authors note that UK maternity statistics have not included miscarriage admissions since 2013.
The evidence is mixed. The Lancet review found signs of rising rates in the USA, China and Sweden but falling rates in Finland. The reasons are unclear, although the authors suggest that people becoming pregnant at older ages may play a part.
Reading statistics after a loss can be painful, and no number can capture what a pregnancy meant to you. Miscarriage UK runs a support line on 0303 003 6464, and Tommy's offers a free helpline on 0800 0147 800. Our miscarriage care page lists further UK support organisations.
This page explains published statistics for general education. It is not a substitute for advice about your own health or pregnancy from a doctor, midwife or genetic counsellor. If you have heavy bleeding, severe pain, a high temperature or feel faint, contact your early pregnancy unit or call NHS 111, or call 999 in an emergency.
Contact
The figures and clinical statements on this page are drawn from the sources below. Guidance evolves — always discuss your individual circumstances with a clinician.
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