The birth of a new baby is always a joyous occasion.
However, for every news of a successful pregnancy, one may also have heard of a friend or relative who has experienced a miscarriage.
A miscarriage, otherwise known as spontaneous abortion, is the unexpected ending of a pregnancy.
It can trigger a lot of emotions, including guilt, fear and sadness.
This can result in certain misconceptions or myths about miscarriages.
This article will address some of the more common myths, as well as explain the common causes and risk factors involved.
Myth or fact?
Miscarriages in early pregnancy are extremely common.
Studies have shown that approximately 8% to 20% of women who know that they are pregnant have a miscarriage some time before 20 weeks of pregnancy.
Eighty percent of those miscarriages occur in the first 12 weeks of pregnancy.
However, actual rates of miscarriages are likely higher, as it can occur even before the pregnancy is known, with some studies estimating that rates could be as high as 30%.
Miscarriages after a 20-week gestation period are relatively rare, accounting for only 1% of total miscarriages.
The truth is that most miscarriages are unpreventable due to factors out of one’s control.
During early pregnancy, more than half of miscarriages are due to chromosomal abnormalities in the embryo.
Extra chromosomes, such as in Down syndrome, can lead to developmental abnormalities, resulting in a spontaneous abortion.
Unfortunately, these abnormalities are not within the control of the parents, and the lack of recognition of this fact often leads to immense guilt for the mother.
Though miscarriages are one of the most common complications of pregnancy, a single miscarriage does not mean that subsequent pregnancies carry an increased risk of miscarriage.
Prospective studies have found that the overall risk of a miscarriage remains at 15% – a baseline risk – after one miscarriage.
However, recurring miscarriages do increase the risk of subsequent miscarriages.
The same study showed that the risk increases up to 31% after two consecutive miscarriages, and up to 46% after three or more miscarriages.
Up to 75% of women believe that maternal stress can induce an abortion, though everyday stressors such as arguments and disagreements with spouses are unlikely to harm the fetus.
However, prolonged exposure to stress, such as living in poor conditions or staying in abusive relationships, can impair one’s mental health and increase the risk of spontaneous abortion.
Similarly, the fetus is unlikely to be affected from falls and minor bumps to the belly as it is well- cushioned in the uterus by strong muscular walls and amniotic fluids.
However, significant trauma such as car accidents, gunshot wounds, or even medical procedures like chorionic villi sampling or amniocentesis, can potentially cause pregnancy losses.
Risk factors
Congenital chromosomal abnormalities make up the most common cause of miscarriages by far.
However, there are also other maternal factors that can lead to spontaneous pregnancy losses:
Abnormalities within the uterus, such as fibroids, adhesions or an incompetent cervix, can lead to second-trimester pregnancy losses.
Various infections have been associated with increased risk of miscarriages.
Untreated syphilis leads to a 21% increased risk of fetal loss and stillbirth, while parvovirus B19, zika and cytomegalovirus infections have been associated with increased risk of pregnancy loss at 8%, 6% and 2.5% respectively.
Increasing maternal age increases the risk of pregnancy loss, with an age of 35 and above being the most significant risk factor due to the risk of fetal chromosomal abnormalities.
Uncontrolled diabetes can result in lethal fetal anomalies and fetal loss.
Fortunately, good sugar control prior to conception can bring the risk back to normal.
Having a body mass index (BMI) of more than 25 increases the risk of pregnancy loss within the first 20 weeks of gestation by nearly 70%.
Both uncontrolled hyperthyroidism or hypothyroidism have been associated with increased risk of pregnancy loss, with some studies suggesting that they can double the baseline risk.
Some unfortunate couples experience recurrent miscarriages.
For women with two or more failures of clinically-recognised pregnancies before 20-24 weeks of gestation, this is termed recurrent pregnancy loss (RPL).
Unfortunately, there is no single treatment available for RPL.
The main goals are for identification and treatment of any reversible maternal and fetal risk factors.
This involves taking a complete medical, surgical, genetic and family history, along with a physical examination.
It may also involve medical imaging of the uterus, genetic analysis of both parents, as well as a full medical workup to identify any underlying medical conditions that the mother may have.
Thankfully, most women with RPL have a good chance of eventually having a successful pregnancy, even when a definitive diagnosis is not made and treatment is not initiated.
In one study, it was found that the overall live birth rates after a diagnosis of RPL was estimated to be around 71% to 77%.
Dr Zeng Shanyong is an internal medicine specialist in Singapore. For more information, email starhealth@thestar.com.my. The information provided is for educational and communication purposes only, and should not be considered as medical advice. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this article. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
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