Miscarriage is relatively common, particularly during the first 12 weeks of pregnancy. For many women, one of the biggest concerns after a positive pregnancy test is whether the pregnancy will continue to develop normally.
The reassuring news is that the risk of miscarriage decreases considerably as pregnancy progresses, particularly after an ultrasound scan confirms that the baby is growing normally and has a heartbeat.
Although miscarriage can be a distressing experience, a single miscarriage is often an isolated event. Most women who experience an early pregnancy loss subsequently go on to have a successful pregnancy.
Understanding the risks at different stages of pregnancy can help provide perspective and reassurance.
Key points
- Approximately one in five recognised pregnancies ends in miscarriage, although the exact proportion depends on when pregnancy is identified.
- Research shows that the risk of miscarriage falls substantially with each passing week when ultrasound confirms that the baby is alive and developing.
- A reassuring ultrasound scan at approximately 12 weeks is an important milestone.
- Most early miscarriages occur because of genetic problems affecting the developing embryo.
How common is miscarriage?
Approximately one in five recognised pregnancies ends in miscarriage, although the exact proportion depends on when pregnancy is identified.
Most miscarriages occur during the first trimester, before 12 weeks of pregnancy. Many losses occur during the earliest weeks, sometimes before a woman knows she is pregnant. Very early losses detected only by a pregnancy test are sometimes called biochemical pregnancies.
The likelihood of miscarriage depends on several factors, including maternal age, previous pregnancy history, the stage of pregnancy and ultrasound findings.
Importantly, the overall risk of miscarriage is different from the remaining risk after a reassuring ultrasound scan. For example, a woman who has just received a positive pregnancy test has a different level of uncertainty from someone whose ultrasound at eight or twelve weeks confirms normal growth and heart activity.
What is the risk of miscarriage at 6, 7, 8, 9 and 10 weeks?
Research shows that the risk of miscarriage falls substantially with each passing week when ultrasound confirms that the baby is alive and developing.
Data from a published study involving women without bleeding or other symptoms showed that the risk of subsequent miscarriage after an ultrasound confirming a heartbeat was approximately:
Remaining risk of miscarriage after a reassuring scan
Risk of subsequent miscarriage after an ultrasound confirming a heartbeat
These figures are specifically for women with singleton pregnancies in which fetal heart activity had already been confirmed at the stated gestational age. They do not represent the risk for every pregnancy at these stages.
The estimates may differ for women who have not yet had an ultrasound scan, those experiencing bleeding, those with previous miscarriages or those with underlying medical conditions.
Nevertheless, the overall message is encouraging. Once a normal heartbeat has been seen, the likelihood of the pregnancy continuing generally improves with each passing week.
Read more: When Can You See a Baby’s Heartbeat on an Early Pregnancy Scan?
What is the risk of miscarriage after a normal 12-week scan?
A reassuring ultrasound scan at approximately 12 weeks is an important milestone.
At this stage, the baby is more developed, the heartbeat is clearly visible and the clinician can assess growth and several aspects of early anatomy.
Research published by Professor Ranjit Akolekar and colleagues examined more than 33,000 singleton pregnancies assessed between 11 and 13 weeks. The study found that, following confirmation of a live baby at the first-trimester scan, the risk of subsequent miscarriage before 24 weeks was approximately 1.2%.
In other words, approximately 99 out of every 100 pregnancies in this study did not subsequently end in miscarriage.
Although no ultrasound examination can guarantee the outcome of a pregnancy, these findings provide considerable reassurance following a normal 12-week scan.
Is the risk of miscarriage different in twin pregnancies?
Yes. Twin pregnancies have a higher risk of pregnancy loss than singleton pregnancies, and the risk depends partly on whether the babies share a placenta.
Dichorionic diamniotic (DCDA) twins
These twins have separate placentas and separate amniotic sacs.
Following a scan showing two live babies at 11–13 weeks, research has reported a risk of losing both babies before 24 weeks of approximately 2%.
Monochorionic diamniotic (MCDA) twins
These twins share one placenta but have separate amniotic sacs.
Because the babies share a placental circulation, there are additional pregnancy risks, including twin-to-twin transfusion syndrome and unequal placental sharing.
Research has reported a risk of losing both babies before 24 weeks of approximately 6% following a scan showing two live babies at 11–13 weeks. The overall risk of losing one or both babies is higher, at approximately 8%.
Twin pregnancies therefore benefit from specialist ultrasound surveillance, particularly when the babies share a placenta.
Risk of miscarriage after a normal 12-week scan
Risk of pregnancy loss before 24 weeks after a scan at 11–13 weeks showing live babies
What are the common causes of miscarriage?
Most early miscarriages occur because of genetic problems affecting the developing embryo.
These usually arise by chance during fertilisation or the earliest stages of development and prevent the pregnancy from developing normally. In most cases, they do not mean that either parent has an inherited genetic condition.
Other factors that may contribute to miscarriage include:
Maternal age
The risk of miscarriage increases with age, particularly after 35 years, largely because genetic changes in eggs become more common.
Medical and hormonal conditions
Poorly controlled diabetes, certain thyroid disorders and other hormonal conditions may increase the risk of miscarriage.
Conditions affecting the uterus
Differences in the shape or internal structure of the uterus may sometimes affect how a pregnancy develops.
Blood-clotting and autoimmune conditions
Certain conditions affecting blood clotting or the immune system, particularly antiphospholipid syndrome, are associated with pregnancy loss.
Lifestyle factors
Smoking, excessive alcohol consumption and some other potentially modifiable factors may increase the risk of miscarriage.
However, many miscarriages occur without any identifiable risk factor. Most importantly, everyday activities such as walking, working, exercising or having sexual intercourse do not ordinarily cause miscarriage.
Does having one miscarriage mean I am more likely to miscarry again?
For most women, a single miscarriage is an isolated event.
It is not unusual for a woman to experience one early pregnancy loss and subsequently have one or more successful pregnancies.
A previous miscarriage may slightly increase the statistical risk in a future pregnancy, but the overall likelihood of having a successful pregnancy remains high.
Extensive investigations are not usually necessary following one uncomplicated early miscarriage, unless there are particular concerns arising from the woman’s medical history or the circumstances of the loss.
What is recurrent miscarriage?
Recurrent miscarriage refers to repeated pregnancy losses. The Royal College of Obstetricians and Gynaecologists (RCOG) defines recurrent miscarriage as three or more miscarriages during the first trimester. These miscarriages do not have to occur consecutively.
However, clinicians may recommend investigations after two miscarriages when the history suggests that there could be an underlying cause.
Repeated pregnancy loss deserves careful assessment because, in some women, an identifiable and potentially treatable condition may be present.
What causes recurrent miscarriage?
There are several possible causes of recurrent miscarriage. Some are well established, while others remain areas of ongoing research.
Genetic conditions
Occasionally, one parent may carry a rearrangement of genetic material that does not affect their own health but increases the chance of an embryo developing with an unbalanced genetic arrangement. Specialist genetic testing may be recommended in selected circumstances.
Antiphospholipid syndrome (APS)
APS is an autoimmune condition in which the body produces antibodies associated with abnormal blood clotting and pregnancy complications.
It is an important, potentially treatable cause of recurrent miscarriage. Diagnosis requires specific blood tests, usually repeated at least 12 weeks apart.
Inherited thrombophilia
Some women inherit conditions that increase the tendency for blood to clot.
These conditions have been linked to certain pregnancy complications, particularly later pregnancy loss, although their association with recurrent early miscarriage is weaker. Routine testing for every inherited thrombophilia is not recommended for all women with recurrent early miscarriage.
Differences in the shape of the uterus
Some women are born with differences in the structure of the uterus, known as Müllerian anomalies.
For example, a septate uterus has a wall of tissue dividing part of the uterine cavity. Certain uterine abnormalities are associated with an increased risk of miscarriage and may be identified using specialist three-dimensional ultrasound.
Hormonal conditions and progesterone
Progesterone is a hormone that supports the lining of the uterus and helps maintain early pregnancy.
Low progesterone levels may be associated with a pregnancy that is not developing normally. However, this does not necessarily mean that progesterone deficiency caused the miscarriage.
There is evidence that progesterone treatment can improve pregnancy outcomes in some women who experience bleeding in early pregnancy and have previously had a miscarriage.
Other hormonal conditions, including thyroid disease and poorly controlled diabetes, may also contribute to pregnancy loss.
Immune-system factors
Researchers have investigated whether abnormalities in the maternal immune response may contribute to some cases of recurrent miscarriage.
However, apart from established conditions such as APS, the evidence for many proposed immune causes remains uncertain. Tests involving natural killer cells and other specialised immune markers are not routinely recommended because their clinical usefulness has not been established.
Unexplained recurrent miscarriage
Despite appropriate investigations, no definite cause is identified in many women.
This can be frustrating, but it does not mean that a future successful pregnancy is unlikely. Many women with unexplained recurrent miscarriage subsequently have a successful pregnancy, particularly with appropriate specialist support and monitoring.
Can anything reduce the risk of miscarriage?
Not all miscarriages can be prevented, particularly those caused by genetic problems arising during early embryo development.
However, some measures can support a healthy pregnancy and address potentially treatable risk factors. These include stopping smoking, avoiding alcohol during pregnancy, maintaining a healthy weight, taking recommended folic acid supplements and ensuring that conditions such as diabetes or thyroid disease are appropriately managed.
Women with recurrent miscarriage may benefit from targeted investigations and treatment when a specific cause is identified.
For example, women with confirmed antiphospholipid syndrome may benefit from treatment with low-dose aspirin and heparin under specialist supervision. Progesterone treatment may also be appropriate for women with early pregnancy bleeding and a previous miscarriage, following confirmation of an intrauterine pregnancy.
There is no single treatment that prevents every miscarriage, and investigations or medication should be guided by individual circumstances and established evidence.
When should I seek medical advice?
If you experience bleeding or abdominal pain during early pregnancy, contact your GP, midwife or local NHS Early Pregnancy Assessment Service for advice.
Seek urgent medical assessment if you develop heavy bleeding, severe abdominal pain, significant one-sided pelvic pain, shoulder-tip pain, dizziness or fainting.
These symptoms may occasionally indicate an ectopic pregnancy or significant bleeding. If you collapse or experience severe symptoms, call 999 or attend an Emergency Department.
If you have experienced two or more miscarriages, particularly where there are other relevant medical or pregnancy factors, it may be appropriate to discuss specialist assessment before attempting another pregnancy.
Read more: Bleeding in Early Pregnancy: What Does It Mean?
Understanding your individual risk
Miscarriage is common, particularly during the earliest weeks of pregnancy, but the risk decreases substantially as pregnancy progresses.
Seeing a normal heartbeat and appropriate growth on ultrasound is reassuring, and the findings of a normal 12-week scan are particularly encouraging.
For most women, one miscarriage is an isolated event, and the likelihood of a successful future pregnancy remains high.
Where miscarriages occur repeatedly, specialist investigations may identify an underlying condition and help guide care in a future pregnancy.
The most useful assessment considers your age, medical history, previous pregnancies and ultrasound findings rather than relying on a single percentage.
Related pregnancy guides
Frequently asked questions
How common is miscarriage?
Approximately one in five recognised pregnancies ends in miscarriage, although the exact proportion depends on when pregnancy is identified.
What is the risk of miscarriage at 6, 7, 8, 9 and 10 weeks?
Research shows that the risk of miscarriage falls substantially with each passing week when ultrasound confirms that the baby is alive and developing.
What is the risk of miscarriage after a normal 12-week scan?
A reassuring ultrasound scan at approximately 12 weeks is an important milestone.
Is the risk of miscarriage different in twin pregnancies?
Yes. Twin pregnancies have a higher risk of pregnancy loss than singleton pregnancies, and the risk depends partly on whether the babies share a placenta.
What are the common causes of miscarriage?
Most early miscarriages occur because of genetic problems affecting the developing embryo.
Does having one miscarriage mean I am more likely to miscarry again?
For most women, a single miscarriage is an isolated event. It is not unusual for a woman to experience one early pregnancy loss and subsequently have one or more successful pregnancies.
Specialist pregnancy care at The Pregnancy Clinic
At The Pregnancy Clinic, we provide consultant-led early pregnancy ultrasound examinations and specialist assessment for women with previous pregnancy loss or concerns about their current pregnancy.
Our approach combines detailed ultrasound assessment, review of your pregnancy and medical history, and evidence-based advice about investigations, treatment and monitoring where appropriate.
For women who have experienced miscarriage, we aim to provide clear information, sensitive support and an individualised plan for future pregnancy care.
Book an early pregnancy scan → Book a consultation →The Pregnancy Clinic is not an emergency service. If you experience severe pain, heavy bleeding, fainting or other acute symptoms, please seek urgent NHS assessment.
Clinical references
- Akolekar R, Bower S, Flack N, Bilardo CM, Nicolaides KH. Prediction of miscarriage and stillbirth at 11–13 weeks and the contribution of chorionic villus sampling. Prenatal Diagnosis. 2011;31:38–45.
- Miscarriage risk for asymptomatic women after a normal first-trimester prenatal visit. 2008.
- Litwinska E et al. Outcome of twin pregnancy with two live fetuses at 11–13 weeks’ gestation. Ultrasound in Obstetrics & Gynecology. 2020.
- RCOG. Recurrent Miscarriage — Green-top Guideline No. 17. 2023.
- RCOG. Recurrent miscarriage — patient information.
- NICE. Ectopic pregnancy and miscarriage: diagnosis and initial management (NG126).