It’s an agonising truth, but a truth nonetheless, that an estimated 15-25% of recognised pregnancies end in miscarriage, with more than 80% occurring within the first three months. A miscarriage refers to a non-viable pregnancy in the uterus or an embryo or foetus without a heartbeat. The most important thing to take away from the notion of a miscarriage is that in the overwhelming majority of cases, there is simply nothing that could have been done to prevent it.
Thanks to celebrities like Mark Zuckerburg, Carrie Underwood and Lily Allen speaking out about their experiences, more and more people are opening up about suffering a miscarriage, which is working towards dismantling the stigma which has surrounded it for so long.
Here are 5 scientific reasons why miscarriages happen.
1. Genetic/chromosomal abnormalities
The most common cause of miscarriage—accounting for around half of all miscarriages—is chromosomal abnormalities. In a lot of cases, this occurs when the foetus has either additional or missing chromosomes. Reassuringly, most chromosomal problems are not inherited, so having one miscarriage does not mean that you are destined to have another one.
Age is thought to play a role in the likelihood of genetic abnormalities. Statistics show that 10% of women have a miscarriage when they are younger than 30 years old, and this rate doubles to 20% between 35 and 39 years old. It goes up to 40% at age 40, and 80% at age 45.
2. Hormonal abnormalities
The most common hormone imbalance which may result in miscarriage is low progesterone—known as luteal phase deficiency. This is common in women with PCOS, but the good news is that, if this happens to you, you can supplement with progesterone post-ovulation in an attempt to prevent it from happening again in the future.
3. Uterine fibroids
Fibroids are benign lumps of tissue that grow in the wall of the uterus—and estimates suggest that anywhere between 20% and 50% of women have some type of fibroid at any given time.
Location and size are thought to be important factors in assessing how likely a fibroid is to cause miscarriage; for example, if the fibroid is closer to the middle of the uterus, where a fertilised egg is more likely to implant, then the fibroid is more likely to cause a miscarriage. Similarly, the bigger a fibroid is, the more blood vessels it contains—and the more it can take blood flow away from the uterus and a developing foetus.
4. Certain lifestyle choices
In the vast majority of cases, miscarriage has nothing to do with lifestyle. Common misconceptions around reasons for miscarriage include too much stress, having sex whilst pregnant and intense exercise—but it’s important to note that there is no medical evidence for any of these things having any bearing on your likelihood for miscarriage.
There is some research to suggest that smoking and alcohol increases the risk of miscarriage, however, many experts argue that smoking and consumption of alcohol should be avoided more because of developmental risks and links to poor outcomes during pregnancy. Some studies have also found a link between excessive (please note the word excessive!) caffeine consumption and miscarriage, which is why health professionals encourage you to limit your coffee habit to one per day whilst pregnant.
5. Other underlying medical problems
Pre-existing, poorly-controlled medical problems like diabetes, thyroid issues, and uncontrolled hypertension, as well as abnormalities of the uterus, can also increase your risk for miscarriage, which is why pre-conception health care is such an important part of trying for a baby.
If you’ve suffered a miscarriage, taking time to heal both physically and emotionally is extremely important. Seek counselling to enable you to process your emotions, and remember that 60-80% of women who have suffered three miscarriages will go on to have healthy, successful pregnancies in the future.