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October 27, 2026

What Causes a Miscarriage? Facts Every Expecting Parent Should Know

Pregnancy is often filled with excitement, anticipation and careful planning. From the first positive pregnancy test to the first ultrasound scan, expecting parents naturally want to do everything they can to support a healthy pregnancy. So when a miscarriage happens, one of the first questions is often: “Why did this happen?”

The answer is not always straightforward. In many cases, a miscarriage occurs because the pregnancy was not developing normally, often due to a random genetic or chromosomal problem. It is usually not caused by something the mother did or failed to do. Understanding the facts about miscarriage can help expecting parents separate medical reality from common myths and recognise when professional care is needed. For couples in Malaysia who have experienced a miscarriage, knowing when to seek medical attention and when further investigation may be appropriate can also help them make informed decisions about future pregnancies.


What Is a Miscarriage?

A miscarriage is the spontaneous loss of a pregnancy during the early stages of pregnancy. Early miscarriage refers to pregnancy loss during the first trimester and is relatively common, affecting approximately one in five women following a positive pregnancy test. Miscarriage may present with vaginal bleeding and abdominal cramps, although some women experience few or no symptoms and the loss may only be detected on ultrasound.

Importantly, bleeding in early pregnancy does not always indicate a miscarriage, and many women who experience bleeding go on to have a healthy pregnancy. Women experiencing bleeding or abdominal pain during pregnancy should seek assessment from their doctor or maternity care provider.


What Causes a Miscarriage?

There are many possible causes and risk factors, but sometimes no specific cause can be identified.

Chromosomal abnormalities

The most common reason for an early miscarriage is a problem with the baby’s chromosomes. Chromosomes carry genetic information needed for normal growth and development. If an embryo has an incorrect number or arrangement of chromosomes, it may not develop normally, and the pregnancy may end in miscarriage. In most cases, these chromosomal abnormalities occur randomly during the formation of the egg, sperm or early embryo. They do not necessarily mean that either parent has a genetic problem. This is one reason why a miscarriage can happen even when both parents are healthy.

Age-related changes

The chance of miscarriage generally increases as maternal age increases, largely because chromosomal abnormalities become more common with age. This does not mean that women in their 30s or 40s cannot have healthy pregnancies. Many do. However, your doctor may discuss age-related pregnancy risks as part of pre-pregnancy or antenatal care. Paternal age may also contribute to pregnancy risks, although maternal age is a more established factor in miscarriage risk.


Health Conditions That May Increase the Risk of Miscarriage

Some medical conditions can increase the likelihood of pregnancy complications, particularly when they are poorly controlled.

Diabetes

Diabetes that is poorly controlled before or during pregnancy can increase the risk of miscarriage and other pregnancy complications. If you have diabetes and are planning a pregnancy, speak with your doctor about getting your blood sugar under good control before conception. This is particularly important because some diabetes medications may need to be reviewed or changed before pregnancy.

Thyroid disorders

Thyroid problems can affect pregnancy. Poorly controlled thyroid disease may increase the risk of miscarriage. If you have an existing thyroid condition, regular monitoring and appropriate treatment before and during pregnancy can help manage the risks.

Polycystic ovary syndrome (PCOS)

PCOS is a common hormonal condition that can affect ovulation and fertility. Some women with PCOS may also have an increased risk of miscarriage. The relationship is complex, and having PCOS does not mean that a woman will have a miscarriage. If you have PCOS and are planning to conceive, discuss your health and pregnancy plans with your doctor.

Problems affecting the uterus

Certain abnormalities in the shape or structure of the uterus can increase miscarriage risk. Examples include some congenital uterine abnormalities, fibroids and scar tissue inside the uterus. Whether a particular condition affects pregnancy depends on factors such as its size, location and effect on the uterine cavity.

Not every fibroid or uterine abnormality requires treatment. A gynaecologist can determine whether further investigation or treatment is appropriate.

Antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune condition associated with abnormal blood clotting. It can increase the risk of recurrent miscarriage and certain other pregnancy complications. If recurrent pregnancy loss is being investigated, your doctor may consider testing for APS depending on your medical history.


Lifestyle and Environmental Factors

Certain lifestyle factors can increase the risk of miscarriage. However, these should be understood in context. Having one risk factor does not mean a miscarriage will definitely happen.

Smoking

Smoking is associated with an increased risk of miscarriage. If you smoke and are planning a pregnancy, stopping as early as possible is one of the most beneficial steps you can take for your health and your baby’s health. This includes avoiding exposure to second-hand smoke where possible.

Alcohol

Alcohol consumption during pregnancy is not considered safe, and alcohol use may increase the risk of pregnancy loss. If you are pregnant or trying to conceive, avoiding alcohol is the safest approach.

Excessive caffeine

High caffeine intake may be associated with increased pregnancy risks. If you are pregnant, speak with your healthcare provider about an appropriate daily caffeine intake. Remember that caffeine is found not only in coffee but also in tea, chocolate, energy drinks and some other beverages.

Being significantly underweight or overweight

Being substantially underweight or overweight may increase pregnancy risks, including the risk of miscarriage. If you are planning a pregnancy, achieving a healthy weight through sustainable lifestyle changes can be beneficial. However, pregnancy is not the time to undertake extreme dieting or weight-loss programmes without medical guidance.


Can Stress Cause a Miscarriage?

This is one of the questions many expecting parents ask. Ordinary day-to-day stress is not considered a cause of miscarriage. Pregnancy can naturally be an emotional time. Work pressures, family responsibilities, financial concerns, relationship difficulties and worries about the pregnancy can all contribute to stress. Feeling stressed does not mean you have harmed your baby. If stress or anxiety becomes overwhelming, speak with your doctor or a mental health professional rather than blaming yourself.


Can Exercise or Sex Cause a Miscarriage?

For most healthy pregnancies, normal physical activity and sexual intercourse do not cause early miscarriage. Sex during pregnancy is not associated with early miscarriage. However, your doctor may recommend avoiding certain activities or intercourse if you have a specific pregnancy complication or have been advised to take precautions. Always follow the advice given by your obstetrician or maternity care team.


Can Everyday Activities Cause a Miscarriage?

Many everyday activities are wrongly blamed for pregnancy loss. A miscarriage is generally not caused by ordinary activities such as walking, working, travelling in a car or having a normal emotional reaction to stress. In Malaysia, pregnant women may hear advice from relatives, friends or social media about certain foods, household activities or traditional practices being responsible for miscarriage. It is important to distinguish cultural beliefs from medically established causes. If you are unsure whether a particular food, supplement, herbal preparation or activity is safe during pregnancy, ask your doctor or pharmacist before using it. This is particularly important for traditional or herbal medicines, as “natural” does not automatically mean safe during pregnancy.


What Are the Warning Signs of Miscarriage?

Symptoms can vary depending on the stage and type of pregnancy loss. Possible warning signs include:

  • Vaginal bleeding or spotting
  • Abdominal cramps
  • Lower abdominal pain
  • Lower back pain
  • Passing tissue or fluid from the vagina
  • A sudden reduction in pregnancy symptoms

However, these symptoms do not automatically mean that a miscarriage has occurred. For example, light bleeding can occur during early pregnancy and some women who experience it go on to have healthy pregnancies.

When should you seek urgent medical attention?

If you are pregnant and experience heavy vaginal bleeding, severe abdominal pain, dizziness, fainting, shoulder-tip pain, fever or feel very unwell, seek urgent medical attention.

These symptoms can sometimes indicate a serious complication, including an ectopic pregnancy, which requires immediate medical assessment. If you are in Malaysia and experiencing a medical emergency, call 999 or go to the nearest emergency department.


How Is a Miscarriage Diagnosed?

If miscarriage is suspected, your doctor may recommend an assessment that can include:

Ultrasound scan

An ultrasound can help determine whether the pregnancy is developing normally and whether a miscarriage has occurred. A transvaginal ultrasound may provide a clearer view during early pregnancy and does not increase the risk of miscarriage.

Blood tests

Your doctor may recommend blood tests, including measurement of β-hCG (human chorionic gonadotropin), depending on your symptoms and ultrasound findings. Sometimes more than one assessment is needed before a diagnosis can be confirmed. This can understandably be an anxious period for expecting parents. Your healthcare team should explain what the results mean and what happens next.


What Happens After a Miscarriage?

If a miscarriage is confirmed, management depends on your individual circumstances. Depending on the situation, options may include:

  • Waiting for the pregnancy tissue to pass naturally
  • Medication to help complete the miscarriage
  • A surgical procedure to remove remaining pregnancy tissue

Your doctor will discuss the appropriate options based on factors such as your symptoms, ultrasound findings, bleeding and overall health. There is also an emotional side to recovery. A miscarriage can bring grief, sadness, anger, guilt, anxiety or a mixture of emotions. Partners can experience grief too. There is no single “right” way to feel after pregnancy loss.


What Is Recurrent Miscarriage?

One miscarriage is usually a one-off event. However, if someone experiences repeated pregnancy losses, further investigation may be recommended. Definitions vary between guidelines and healthcare systems. RCOG currently defines recurrent miscarriage as three or more early miscarriages. Possible investigations may include:

  • Blood tests for certain conditions such as APS
  • Thyroid testing
  • Diabetes assessment when appropriate
  • Genetic testing in selected circumstances
  • Ultrasound examination of the uterus

Not every couple will have an identifiable cause. In fact, many cases of recurrent miscarriage remain unexplained. Importantly, unexplained recurrent miscarriage does not mean that a future pregnancy cannot be successful.


Can a Miscarriage Be Prevented?

Unfortunately, many miscarriages cannot be prevented, particularly those caused by random chromosomal abnormalities. However, there are steps that can support a healthier pregnancy:

Before pregnancy

If you are planning to conceive:

  • Attend a pre-pregnancy health assessment if appropriate
  • Take folic acid as recommended
  • Stop smoking
  • Avoid alcohol
  • Maintain a healthy weight
  • Review existing medical conditions
  • Discuss medications with your doctor
  • Check whether vaccinations are up to date
  • Discuss any previous pregnancy complications

If you have diabetes, thyroid disease, PCOS or another chronic condition, managing it before conception can be particularly important.

During pregnancy

Once pregnant:

  • Attend your antenatal appointments
  • Take prescribed medicines as directed
  • Follow recommended screening and ultrasound schedules
  • Eat a balanced diet
  • Avoid alcohol and smoking
  • Check with your doctor before taking new medicines or supplements
  • Seek medical advice if you experience concerning symptoms

In Malaysia, antenatal care may be provided through government health facilities, private obstetricians, hospitals or other maternity services. Choose a healthcare provider you are comfortable with and attend your appointments consistently.


Most Importantly: A Miscarriage Is Usually Not Your Fault

After a miscarriage, it is natural to replay the days and weeks beforehand.

  • “Did I work too hard?”
  • “Did I eat something wrong?”
  • “Was I too stressed?”
  • “Could I have prevented it?”

For most early miscarriages, the answer is no. Chromosomal abnormalities are a major cause of early miscarriage, and these often happen randomly. Even when a risk factor is present, it does not mean the parent caused the miscarriage. WHO has highlighted the importance of recognising miscarriage and pregnancy loss as significant experiences that can carry grief, stigma and emotional distress. Parents deserve compassionate care and support – not blame.


Planning for a Future Pregnancy After Miscarriage

For many couples, one of the biggest questions after a miscarriage is: “When can we try again?” The answer depends on your physical recovery, emotional readiness and individual medical circumstances. Many women go on to have successful pregnancies after a miscarriage. Most miscarriages are a one-off event and that there is a good chance of a successful pregnancy in the future.

If you have experienced recurrent miscarriages, have a known medical condition or have concerns about fertility, a pre-pregnancy consultation with an obstetrician or fertility specialist can help identify any issues that may need attention before trying again.


When Should You Speak to a Fertility Specialist?

A miscarriage does not automatically mean that you have a fertility problem. However, specialist advice may be helpful if you have experienced recurrent miscarriages, difficulty conceiving, certain medical conditions or other concerns about your reproductive health. A fertility team can assess both partners when appropriate and may recommend investigations based on your individual history.

Supporting Your Journey Towards Parenthood

If pregnancy loss has made you anxious about trying again, you do not have to navigate the journey alone. At Avisena Specialist Hospital 2, our fertility unit brings together fertility specialists, embryologists and experienced clinical nurses to provide comprehensive medical care and personalised attention in a supportive environment.

Make your dreams of parenthood a reality with us. Your journey begins here, in the good hands of our fertility specialists, embryologists and experienced clinical nurses. We work together to ensure that you receive high-quality and comprehensive medical care as well as personalised attention, all within a calming and stress-free environment.

For more information or to schedule an appointment, visit our:

Fertlity Unit


The Bottom Line

A miscarriage can be one of the most difficult experiences an expecting parent can go through. Understanding what causes a miscarriage can help, but it is equally important to understand what does not cause one. Most early miscarriages occur because the pregnancy did not develop normally, often because of chromosomal abnormalities. Other factors, including certain health conditions, age, smoking, alcohol use and problems affecting the uterus, can also influence miscarriage risk.

But a miscarriage is usually not caused by something you did, ate, thought or felt. If you experience bleeding or pain during pregnancy, contact your healthcare provider for assessment. If symptoms are severe or you feel seriously unwell, seek emergency medical attention. On the other hand, if you have experienced a miscarriage, give yourself permission to grieve and seek support. With appropriate medical care and, when needed, specialist assessment, many people who experience pregnancy loss go on to have a healthy pregnancy in the future.


Frequently Asked Questions

What is the most common cause of miscarriage?

The most common cause of early miscarriage is believed to be a chromosomal abnormality in the developing pregnancy. These abnormalities often occur randomly and do not necessarily mean either parent has a genetic problem.

Can stress cause a miscarriage?

Ordinary stress is not considered a cause of miscarriage. However, severe or persistent stress can affect your overall wellbeing. If you are struggling with anxiety or emotional distress during pregnancy, speak with your healthcare provider.

Can exercise or sex cause miscarriage?

For most healthy pregnancies, normal physical activity and sex are not associated with early miscarriage. However, your doctor may recommend specific restrictions if you have a pregnancy complication or another medical reason.

Does having one miscarriage mean I will miscarry again?

Not necessarily. Most miscarriages are one-off events, and most women who experience an early miscarriage subsequently have a good chance of a successful pregnancy.

When should I see a fertility specialist after a miscarriage?

One miscarriage does not necessarily require fertility treatment. However, specialist assessment may be appropriate after recurrent miscarriages, difficulty conceiving, certain medical conditions or other reproductive health concerns. A fertility specialist can advise whether further investigations are appropriate for you and your partner.


Medical Disclaimer: This article is intended for general health education and does not replace personalised medical advice. If you are pregnant and experience heavy bleeding, severe abdominal pain, fainting, dizziness or feel seriously unwell, seek urgent medical attention. In Malaysia, call 999 for emergency assistance.



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