G'day team,

Today I'm going to write about a topic that is often considered hush-hush and is neither understood nor spoken about nearly enough in modern society. Given how common miscarriage is it's surprising that people often consider it such taboo, so let's have a chat about it here!

Image source

How Common?

Miscarriage is common, like, astoundingly common. I'm going to pause for a minute and ask you a question...

What percent of fertilized eggs end up being miscarried, in a healthy 30 year old woman?

(Answer below)

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~75%

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Now the first thing I'm going to say is this is a contentious statistic. The reason being is that the majority of miscarriages occur in the first few weeks of pregnancy, before a woman may even know she's pregnant. Studying these early miscarriages is incredibly difficult, and our understanding of this data stems from just a few pieces of research.

A few weeks into a pregnancy (around 6) a fetal heartbeat becomes detectable and from this stage on we have a very good understanding of miscarriage rates and causes. At six weeks miscarriage probability is down to just 10%, and they continue to drop rapidly. Because miscarriage is defined as the loss of heartbeat or expulsion of a fetus before it's able to live independently, we only count the loss of a fetus as miscarriage rates up to 20 weeks.

The table below outlines the expected miscarriage rates as pregnancy progresses...

Week	Miscarriage Risk
Week 0	~75%
Week 6	~10%
Week 10	~2.5%
Week 14	~1%
Week 18	~0.2%

All figures assume Age 30, BMI 22, No previous pregnancies

As we can see, miscarriage rates decrease rapidly as pregnancy progresses. To understand this we really need to have a look at the causes of miscarriage.

Cause

There are many causes of miscarriage, and they can stem from defects in the development of the embryo or placenta, or from infections or anatomical abnormalities of the uterus.

The most common cause of miscarriage is chromosomal abnormalities, and account for 50-65% of all miscarriages.

Human DNA (or genome) is made up of two sets of 'chromosomes'. Chromosomes are bundles of DNA and when we produce sperm or eggs we split our genome, providing each sperm/ egg with one set of chromosomes so that when they meet their counterpart they can produce a whole genome. However this process does not always work perfectly, and damaged chromosomes or abnormal numbers often lead to failure or embryological development very early on.

This is the reason that early miscarriage is the most common. Because the cause in these situations is the development of an embryo that would never have been viable. The other reason that miscarriage rates drop rapidly during pregnancy is that all of the vital life-supporting components of pregnancy (yolk sac, placenta heart etc.) develop in this period. Other causes of miscarriage include...

• Infection (Either viral or bacterial)
• Improper implantation (Wrong site, or badly attached to the endometrial blood supply)
• Maternal diabetes
• Maternal thyroid disease (particularly hypothyroid)
• Maternal polycystic ovary syndrome
• Maternal uterine abnormalities
• Maternal blood abnormalities
• Maternal Lupus
• Trauma
• Malnutrition

Now some of these are factors that are impossible to control, but some are largely influenced by lifestyle and choices made on a day-to-day basis. This being said, even in an individual who's perfectly healthy and makes all the right choices, still has a very real risk of miscarriage. To get a better understanding of an individuals chances of miscarriage we should look at risk factors.

Risk Factors

Age

The risk of miscarriage doubles between the ages of 35 and 40. The graph below outlines the miscarriage rates for confirmed pregnancies with a heartbeat in IVF patients. Rates are much lower in this group, but it gives a good idea of how rates change with age.

Image source

Previous miscarriages

A woman who's had one miscarriage is at a higher risk of miscarriage in future pregnancies.

Smoking, Hypertension, Diabetes, and Obesity

All of these classic markers of 'ill health' can contribute to miscarriage risk. One of the most important parts of fetal development is the growth of a reliable blood supply and this can be compromised by the factors above.

Alcohol and Drugs

Use of alcohol and other drugs, including many medications, can increase the risk of miscarriage. This is one of the reasons that doctors often alter medication regimes for infections and many other medical conditions in pregnant women.

Invasive testing

Some tests that are used to check the health of a child, also carry a risk of miscarriage. The most notable are amniocentesis and chorionic villus sampling. Both of these tests carry a spontaneous abortion risk of under 1%, however, it's something all parents should be aware of going into the procedure.

Impacts

There are some very serious implications of miscarriage on a woman's health, and this is the area that is often most overlooked when people consider miscarriage. In a recent study conducted in London found that 40% women who'd experienced a miscarriage suffered significant changes to relationships with family, friends, and partners.

Depression is a common symptom experienced after many miscarriages and can affect both a potential mother and father alike. For some people these feelings of depression do not digress and progress to Major Depressive Disorder may occur. Other mental health problems can also arise, including Mania, Bipolar Disorder and Generalized Anxiety Disorder.

For women with serial miscarriages, the risk of progressing to these mental health issues is higher. As it is with women who lack social support, have a history of mental health issues or have substance abuse disorders.

One of the reasons the fallout from a miscarriage is so severe is that there's a systemic misunderstanding of how miscarriages occur, and a taboo surrounding the topic can make reaching out for help incredibly difficult. So let's bust some myths that surround miscarriage.

Myths

One Miscarriage Makes Another Inevitable

For a woman who's had one miscarriage, chances of a successful pregnancy in a future are still incredibly high. Remember most miscarriages are not detected and occur so early in pregnancy that neither medical testing nor biological changes could even find the pregnancy.

Miscarraige is Uncommon

If you've read the article you'll know just how insane this one is!

Any Bleeding Indicates a Miscarriage

While it is implrtant to seek medical attention for unwarranted bleeding in early pregnancy, this does not immediately rule out chances of a healthy and normal pregnancy.

Having a Previous Abortion Increaases the Risk of Miscarriage

There is no medical consensus, or strong evidence, that having an abortion increases future risks of miscarriage

Miscarriage is a Mothers Fault

This is perhaps the most pervasive and inaccurate myth that surrounds miscarriage. As we've seen above the vast majority of miscarriages occur simply due to bad luck and are in no way indicative of any fault or failing in the mother!

It's important to remember, when considering a healthy pregnancy, that aside from doctors and midwives, you should take advice witha grain of salt. A lot of people will tell you what worked for them or what they've heard, but this can lead to undue feelings of guilt if a pregnancy is lost and that advice wasn't followed.

Birth is a miraculous phenomenon, but like all biological processes it relies on a degree of luck and is by no means fool proof. Offering support to women whove experiences miscarriage, being open about the topic and supporting any women who's going through pregnancy (regardless of the personal choices she makes about her pregnancy) are all great steps in removing the damage miscarriage can do!

Thanks

Thanks for reading, team, I hope everyone learned something and enjoyed reading this as much as I did writing it. Feel free to keep posted for more medical content :)

Thanks

-tfc

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Resources
Healthline
Diagnosis and management of miscarriage
Datayze
New Kids-Centre
Medscape
Parenting.com
Pregnancy and Baby Birth
Gender comparison of psychological reaction after miscarriage—a 1-year longitudinal study
Mania and depression in the perinatal period among women with a history of major depressive disorders

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My Other Medical Posts

• Human Chimera - Exploring human-human genetic fusions
• Pseudopseudohypoparathyroidism –a breakdown of the longest word in the world and the medical condition it refers to.
• Missunderstood Body Functions
• Human Anatomy 101 - The Heart (Basics)
• Exercising to Death - What is Rhabdomyolysis
• Metabolic Syndrome - What it is, and why it's KILLING US ALL!!!
• Why is Antibiotic Resistance So Hard to Combat?
• Super Bugs - What is antibiotic resistance and how we are fighting it
• Homeostasis - How our body works