What is a miscarriage?

Miscarriage is the spontaneous loss of a pregnancy before the 23rd week. About 10 percent of known pregnancies end in miscarriage. The actual percentage of miscarriages may be higher because many miscarriages occur so early in pregnancy that a woman doesn’t realize she’s pregnant.

What are the symptoms of miscarriage?

The physical signs of a miscarriage are usually cramping and bleeding. Whilst it might provide little comfort to those experiencing a pregnancy loss, the reality is that miscarriages often happen for no obvious reason and can rarely be prevented.

How common is miscarriage?

The topic of miscarriages remains fairly taboo, with many women reluctant or unable to talk about their experience. 

This is despite the fact that miscarriages are common, affecting approximately 1 in 8 known pregnancies, with many more likely to have occurred before a woman knows that she is pregnant. Approximately 1% of women will experience recurrent miscarriages, meaning they have three or more miscarriages in a row.

The risk of miscarriage reduces as a pregnancy progresses. About 80% of miscarriages happen during the first trimester, with fewer than 1% occurring after week 20 of pregnancy. This is why many women wait until they have reached 12 weeks before telling others they are pregnant.

What percentage of pregnancies end in miscarriage?

Fertilisation occurs when a sperm from the male fertilises a female’s egg. Approximately 1 in 3 successful fertilisations will result in a live birth. 

Many potential pregnancies fail prior to implantation and before a woman even realises that she is pregnant. Approximately 15% of clinical pregnancies (meaning an ultrasound has been used to confirm the successful implantation of the fertilised egg into the wall of the uterus) end in miscarriage, usually as a result of chromosomal abnormalities in the embryo.

It is significantly less common for a miscarriage to occur between weeks 12 and 20, so much so that many women are confident to share their news after their 12 week scan. Losses after week 12 are termed late miscarriages and occur in approximately 4% of cases.

What causes miscarriage?

Approximately 50% of miscarriages that happen during the first trimester are due to a chromosomal problem with the developing foetus. Usually there will be the wrong number of chromosomes – too many, or too few – which means the foetus is unable to survive. The risk of chromosomal abnormalities is higher in older women, which is one of the reasons why older mothers are more likely to experience miscarriages than younger women. In women over 45, the risk of miscarriage can be as high as 50%.

Other factors that can result in early pregnancy loss include improper implantation of the fertilised egg, issues with the development of the placenta, structural problems in the female reproductive system, chronic conditions (eg. diabetes, kidney disease, thyroid disease), and a problem with the male’s sperm.

Infections and severe food poisoning can both increase the risk of miscarriage. This is one reason why women are advised to consider their diet during pregnancy and avoid food types that are associated with a higher risk of food poisoning, such as unpasteurised dairy, undercooked meats, raw eggs, and raw shellfish. Pregnant women should also limit the amount of tuna and other large fish due to potential mercury content which may affect the healthy development of the child’s nervous system.

Could lifestyle choices affect my chances of miscarrying?

Yes, lifestyle factors can increase the risk of miscarriage. For example:

• Chronic conditions such as obesity, diabetes and cardiovascular disease. 
• Smoking
• Drug taking
• Alcohol
• Excessive caffeine consumption (try to limit consumption to below 200mg per day).
• Environmental toxins/workplace hazards, e.g. working with radiation. 

You should check with your healthcare provider before taking any medication during pregnancy as not all medicines are appropriate to take at this time. Specific examples of drugs that are best avoided include, retinoids (used for improving skin conditions), methotrexate (used for cancer and other autoimmune disorders such as arthritis) and non-steroidal anti-inflammatories (used for pain relief). 

Why do late miscarriages occur?

Experiencing a miscarriage during the second trimester can be particularly difficult to cope with. By that point, you will have made it through the period that is typically considered to be most high-risk (the first 12 weeks) and are likely to have started announcing your pregnancy others and forming plans.

Throughout pregnancy, women are encouraged to continue to consume a healthy diet and avoid smoking, drinking alcohol and taking recreational drugs. It is also important to ensure that chronic health conditions are under control and any medication is approved as safe for use during pregnancy by your doctor. 

Unfortunately, as with early miscarriages, some late miscarriages are unavoidable. Sometimes the uterus is an abnormal shape, or has obstructions, such as the growth of fibroids which can  increase the risk of miscarriage.

In some cases, a woman will have a weakened/incompetent cervix, which widens and opens prematurely during pregnancy. The cervix should remain closed until just before delivery. This muscular weakness can be due to previous injury, or surgery to the cervix. One treatment option for this is to undergo a cervical cerclage.  

I have an underlying health condition: does that make me more likely to miscarry?

Some women have long-term (chronic) health conditions, which increase their risk of miscarriage, particularly if the condition is not well managed. Examples include:

• Diabetes
• Hypertension
• Auto-immune diseases (lupus)
• Kidney disease
• Thyroid issues
• Polycystic Ovary Syndrome (PCOS).

Does PCOS increase my risk of miscarriage?

The connection between infertility and PCOS is well established. Emerging evidence suggests that even if conception is successful, women with the condition are 2.5 times more likely to miscarry than their healthy counterparts. It is not yet clear whether ovulation induction therapy, using clomiphene citrate for example, increases a woman’s risk of miscarrying; the available data to date is low quality and conflicting. However, women in this category usually have an underlying medical condition, such as diabetes or obesity, that has prompted their use of ovulation induction and may, therefore, already be at higher risk of miscarriage.   

What factors do NOT increase the risk of miscarriage?

Despite concerns to the contrary, the following are not likely to cause a miscarriage:

• The mother’s emotional state (although remaining happy and calm throughout your pregnancy is definitely recommended and you should seek professional help if you do start to feel overwhelmed, anxious or depressed).
• Experiencing a shock or fright.
• Sexual intercourse. For most couples, continuing to have an intimate relationship during pregnancy is perfectly safe, provided of course, both parties want to. If your pregnancy is high risk, or you have had significant bleeding, your doctor might advise you to abstain.
• Moderate exercise.You should always check with a professional before commencing any physical activity.
• Flying.
• Spicy food.

If I have already had one miscarriage, how likely am I to have another?

Having one miscarriage does not usually place a woman at increased risk of having another miscarriage. However, having two or more consecutive miscarriages does increase her risk.  

The European Society of Human Reproduction and Embryology (ESHRE) defines recurrent miscarriage (RM) as three or more consecutive losses occurring before 20 weeks gestation. 

Women who experience RM have a 43% chance of experiencing further miscarriages. Approximately 1% of couples who are attempting to conceive experience RM.

What causes recurrent miscarriage?

Various factors have been associated with RM including parental chromosome abnormalities (10 times more prevalent in couples who have experienced RM, than in the general population). These include: 

• Immune dysfunction
• Endocrine disorders (thyroid conditions and PCOS)
• Damage to the DNA in the male’s sperm
• Uterine structural abnormalities (endometriosis). 

However, in approximately 50% of cases of RM, the exact cause is unknown.  

How are miscarriages diagnosed?

To diagnose a miscarriage, your healthcare provider will conduct one or more of the following tests:

• Pelvic exam. Your health care provider might check to see if your cervix has begun to dilate.
• Ultrasound. During an ultrasound, your health care provider will check for a fetal heartbeat and determine if the embryo is developing normally. If a diagnosis can’t be made, you might need to have another ultrasound in about a week.
• Blood tests. Your health care provider might check the level of the pregnancy hormone, human chorionic gonadotropin (HCG), in your blood and compare it to previous measurements. If the pattern of changes in your HCG level is abnormal, it could indicate a problem. Your health care provider might check to see if you’re anemic — which could happen if you’ve experienced significant bleeding — and may also check your blood type.
• Tissue tests. If you have passed tissue, it can be sent to a lab to confirm that a miscarriage has occurred — and that your symptoms aren’t related to another cause.
• Chromosomal tests. If you’ve had two or more previous miscarriages, your health care provider may order blood tests for both you and your partner to determine if your chromosomes are a factor.

(Source: Mayo Clinic)

What is a “missed miscarriage”?

A missed miscarriage, also known as a silent miscarriage or missed abortion, occurs when a fetus is no longer alive, but this fact is not recognised by the body and the pregnancy tissue is not expelled. Because of this, the placenta may continue to release hormones, and you may continue to experience signs of pregnancy. (Source: NHS England)

What should I do if I miscarry?

If a miscarriage is diagnosed, there are a few management options. The first is to allow your body to complete the miscarriage on its own without intervention. This is only an option if you are early in pregnancy and you are medically stable (for example, your bleeding is not dangerously heavy).

Another option is to take medication to help your uterus contract and complete the miscarriage. While this is often successful in earlier miscarriages, sometimes surgery is needed if the medication doesn’t work or you start to bleed too much. Lastly, a dilation and curettage (or D&C) is a surgical option to treat a miscarriage. This can be chosen as a first line treatment, or  if waiting or taking medicine does not work. Since every case needs to be tailored to the individual, it is important to make an informed decision with your doctor to select the option that is right for you.

How long should I wait after a miscarriage before attempting to conceive again?

In the last set of guidelines published by the World Health Organisation in 2005, it was recommended that couples wait 6 months after miscarriage before attempting to conceive again. However, more recent work has disputed this and even found that couples who fell pregnant within three months of miscarrying got pregnant faster had a higher live birth rate and were no more likely to experience complications, when compared to those who waited for longer than 3 months to start trying to conceive.

What is absolutely essential to consider before trying to conceive after a miscarriage is whether you are ready emotionally. Always consult your healthcare professional who may advise you to wait more or less dependent on the stage of your miscarriage, your physiological and emotional condition. Whilst your body may be physically fit, it is important to remember that you have experienced a loss and, as such, may still be grieving. Giving yourself time to heal mentally is just as important as allowing your body to recover.

Should I wait longer after a miscarriage before attempting to conceive again if I have miscarried more than once?

If you have experienced recurrent miscarriage, your doctor will likely have screened both you and your partner for chromosomal potential abnormalities. If any of these screens came back positive, it is important to consider what the implications are for future pregnancies, prior to attempting to conceive again. The type of abnormality will determine whether you are capable of carrying a pregnancy to term and how likely it is that children you give birth to will have genetic disorders. Your doctor, along with a genetics counsellor,  will be able to counsel and advise you accordingly.