Causes of Abortion – Golden Article

Causes of Miscarriage

In many cases, the primary cause of miscarriage (referred to in English as “miscarriage”) remains unidentified, despite the numerous factors that can contribute to it. Generally, miscarriages that occur during the first trimester are often due to issues related to the fetus itself. In contrast, those happening after the initial three months may be linked to specific health problems experienced by the mother. This article will outline the various causes of miscarriage in more detail.

Genetic Disorders and Congenital Defects

Genes are the fundamental units of heredity that define a person’s physical characteristics, such as gender, blood type, hair color, and eye color. These genes are carried on small structures known as chromosomes within cells. Consequently, abnormalities in the chromosomes of either the father’s sperm or the mother’s egg may trigger a miscarriage during the first trimester or even the early stages of pregnancy. Genetic disorders and congenital defects can lead to the death of the fetus after 20 weeks of gestation. Often, these genetic anomalies occur spontaneously and are not linked to the health of the parents; they arise from errors during the growth and division of the embryo’s cells, preventing normal development and resulting in a miscarriage. It’s important to note that while some genetic disorders can be inherited, possessing such genetic traits does not necessarily inhibit a successful pregnancy but may increase the risk of miscarriage. In general, genetic disruptions can lead to various complications, including:

Intrauterine fetal demise: In this situation, the fetus may develop normally but ceases to grow and dies before any symptoms of pregnancy loss appear.
Molar pregnancy: Both complete and partial molar pregnancies are non-viable. They may be associated with cancerous changes in the mother’s placenta. A complete molar pregnancy occurs when both sets of chromosomes come solely from the father, leading to abnormal placenta growth without fetal development. Partial molar pregnancies occur when one set comes from the father with one from the mother, resulting in a series of placental abnormalities and potentially an underdeveloped fetus.
Blighted ovum: This common miscarriage type occurs early in pregnancy (between weeks five and six), often before the woman realizes she is pregnant. A blighted ovum arises from high levels of chromosomal abnormalities in the embryo, preventing proper development. This condition typically results in the formation of a sac without a fetus within the uterus.
Trisomy: This chromosomal disorder results in a fetus with an additional chromosome. The normal chromosome count in humans is 23 pairs (46 in total). Trisomy increases the risk of miscarriage; however, if the pregnancy continues, it can lead to congenital disabilities, such as Down syndrome.
Nullisomy: This condition occurs when a fetus lacks a complete pair of chromosomes, preventing proper growth and resulting in miscarriage.
Monosomy: In this case, the fetus is missing one chromosome, leading to a total of 45 instead of 46. This condition often results in miscarriage, though in rare instances the pregnancy may continue. If carried to term, the baby may be born with certain birth defects or may have a limited lifespan outside the womb.

Chemical Pregnancy

Chemical pregnancy refers to early miscarriage that occurs shortly after implantation, typically before the pregnancy reaches five weeks. In these cases, pregnancy tests can yield positive results while the mother may not exhibit any symptoms of pregnancy loss, such as missing a menstrual period. The accompanying signs of early miscarriage are generally mild and can be mistaken for standard pre-menstrual symptoms, such as abdominal pain or light vaginal bleeding. Thus, a woman may unknowingly experience a chemical pregnancy and miscarriage without ever realizing she was pregnant.

Placental Issues

The placenta is a vital organ that develops during pregnancy, usually attaching to the upper or side wall of the uterus. The umbilical cord connects the fetus to the placenta, which serves to transport blood from the mother to the child, supplying necessary oxygen and nutrients. Problems with the placenta can sometimes lead to miscarriage. These issues may include:

Toxin transfer: Certain toxic substances, such as alcohol, excessive caffeine, environmental pollutants, non-prescription medications, or illicit drugs, can be transported from the mother to the fetus, resulting in placental complications.
Transfer of harmful cells: The mother may pass harmful cells to the fetus, often stemming from infections or uncontrolled chronic health conditions.
Placental insufficiency: This occurs when the placenta does not develop properly, leading to inadequate blood supply to the fetus, which adversely impacts its growth and development. This condition often arises when the placenta cannot produce enough hormones, antibodies, oxygen, and nutrients, particularly in cases of multiple pregnancies.

Cervical Insufficiency

Cervical insufficiency typically results in miscarriage during the second trimester due to the inability of the cervix to maintain the pregnancy. Common symptoms preceding a miscarriage in this scenario may include sudden pressure, leaking of amniotic fluid, and the expulsion of fetal tissue without significant pain.

Uterine Issues

The chances of miscarriage during the second trimester are higher with certain uterine abnormalities, such as having an irregular shape, limited space, or the presence of uterine fibroids. Some of these conditions include:

Bicornuate uterus: This heart-shaped abnormality increases the risk of miscarriage and preterm birth, although it generally does not impede conception or cause issues during early pregnancy.
Unicornuate womb: This rare condition, where only one side of the uterus develops, results in a uterus that is half the usual size, leading to increased risks of ectopic pregnancies, late-stage miscarriages, and preterm deliveries.
Septate womb: This involves the uterus being divided by a muscular septum, either partially or completely. This condition raises various risks, including difficulties in conceiving, miscarriages in the first trimester, and preterm birth.
Arcuate womb: Similar to a typical uterus but with a slight indentation at the top, this condition can sometimes increase the risk of miscarriage in the second trimester, though it does not significantly affect first-trimester losses or preterm deliveries.

Chronic Health Conditions

Certain chronic health issues can elevate the risk of complications during pregnancy, potentially leading to miscarriage, especially during the second trimester. Key conditions include:

Uncontrolled diabetes or gestational diabetes.
Endometriosis.
Hormonal imbalances.
Obesity.
Crohn’s disease.
Antiphospholipid syndrome.
Multiple sclerosis.
Celiac disease.
Polycystic ovary syndrome (PCOS), which manifests due to hormonal shifts, resulting in the presence of multiple cysts in the ovaries.
Severe or poorly controlled thyroid disorders, such as hypothyroidism or hyperthyroidism.
Thrombophilia, a genetic disorder causing increased blood clotting, may lead to recurrent miscarriages or losses in later stages of pregnancy.
Other health conditions, including chronic kidney disease, lupus, and hypertension; any such disorder in a pregnant woman that remains untreated during pregnancy can heighten the risk of miscarriage.

Medications

It is vital that women consult their doctors before taking any medications or supplements during pregnancy, as some drugs require careful consideration of their potential benefits and risks for both the mother and child. Certain medications should be strictly avoided during pregnancy due to their potential to cause miscarriage or congenital disabilities if their components cross over to the fetus via the placenta. It’s also worth noting that clinical safety trials for new medications often do not include pregnant individuals, making their use uncertain. Some medications known to increase the risk of miscarriage include:

Misoprostol: Commonly used for treating rheumatoid arthritis.
Retinoids: Utilized for skin disorders, such as acne and eczema.
Methotrexate: Prescribed for autoimmune diseases, including rheumatoid arthritis.
Non-steroidal anti-inflammatory drugs (NSAIDs): Used to alleviate inflammation and pain, for example, ibuprofen.

Infections

Minor infections can adversely affect the fetus, potentially leading to miscarriage. Additionally, severe infections that significantly deteriorate a mother’s health can also result in pregnancy loss. Common infections associated with miscarriage include:

Bacterial vaginosis: Characterized by an overgrowth of naturally occurring vaginal bacteria, increasing the risk of miscarriage during the second trimester.
Rubella: This mild infection, known as German measles, can lead to miscarriage, stillbirth, or congenital defects if contracted during pregnancy. Screening for immunity typically occurs during a woman’s first prenatal visit, and vaccinations are available to prevent rubella.
Malaria: Spread by the bite of an infected mosquito, malaria can cause symptoms such as fever, chills, headache, and nausea. Pregnant women are three times more likely to experience severe malaria, thus increasing the risk of miscarriage, stillbirth, and low birth weight.
Dengue fever: As one of the most common mosquito-borne infections, it typically presents mild symptoms but may indirectly contribute to miscarriage.

Food Poisoning

Food poisoning results from consuming contaminated food, which can increase the risk of miscarriage during pregnancy. Pregnant women should exercise caution when handling food and avoid consuming foods at risk for infection while maintaining proper hand hygiene. Some foods that may cause food poisoning include:

Raw or undercooked eggs, which may contain Salmonella.
Poorly cooked meat, potentially causing toxoplasmosis.
Fresh dairy products or unpasteurized milk, such as soft cheeses, which may harbor Listeria that can cause listeriosis.

Other Causes

Miscarriages can also result from less common factors compared to those mentioned earlier, such as:

Histamine intolerance.
Uterine fibroids.
Asherman’s syndrome: Characterized by the presence of adhesions or scarring within the uterus.

Risk Factors for Miscarriage

Numerous factors can increase the risk of miscarriage, which may include the aforementioned causes as well as other elements. Key risk factors include:

A history of previous miscarriages; the risk heightens for women who have experienced two or more consecutive losses.
Tobacco use or substance abuse.
Undergoing invasive prenatal testing, including chorionic villus sampling and amniocentesis, which may carry a slight miscarriage risk.
Age: Women aged 35 and older are at a higher risk of miscarriage compared to younger pregnant women. A study published in the British Medical Journal in 2019 indicated that the miscarriage risk for women aged 25 to 29 was about 10%, while it sharply increased to 53% for those aged 45 or older.
Being underweight or overweight prior to pregnancy.
Exceeding 200 milligrams of caffeine per day.
Rh incompatibility: This occurs when the mother is Rh-positive, and the fetus is Rh-negative.
Fever: Elevated body temperature in the mother (37.8°C or higher) increases miscarriage risk.
Short intervals between pregnancies; a gap of less than six months between a completed pregnancy and the next can slightly elevate miscarriage risk, potentially leading to preterm births.
Exposure to environmental toxins and hazards; studies indicate an increased risk of miscarriage linked to substances like lead, mercury, and organic solvents.
History of sexually transmitted infections (STIs), such as syphilis or certain viral hepatitis strains.
Low vitamin D or B12 levels, or excessive vitamin A intake, which can negatively impact pregnancy outcomes.

Preventing Miscarriage

As previously mentioned, certain miscarriage causes are difficult to prevent, particularly chromosomal disorders. However, if a miscarriage is linked to a controllable issue, certain measures can be taken to improve the likelihood of a successful pregnancy. Below are some recommendations for preventing miscarriage:

Receive regular prenatal care through consistent medical examinations, which is crucial for addressing pregnancy complications.
Avoid exposure to previously addressed miscarriage risk factors.
Identify and manage chronic medical conditions that may contribute to miscarriage before becoming pregnant, such as hypertension or diabetes, by regularly monitoring blood sugar levels, maintaining a healthy weight, exercising regularly, eating a balanced diet, and adhering to prescribed medications.
Create a healthy environment for pregnancy and maintain it throughout gestation to ensure optimal fetal growth. This can involve:

Avoiding smoking and secondhand smoke.
Consulting a doctor before using any medications or supplements.
Limiting caffeine intake.
Steering clear of environmental hazards.
Refraining from high-impact physical activities or sports that present injury risks.

Adopt a balanced lifestyle and diet by including five servings of fruits and vegetables daily, ensuring adequate intake of folic acid and calcium, and taking any prenatal vitamins recommended by a healthcare provider.
Maintain a healthy weight.
Avoid undercooked meats, soft cheeses, and other foods that may pose a risk of food poisoning.
Know your family’s medical and genetic history.
Ensure to receive recommended immunizations.
Consult a physician if experiencing symptoms such as fever, heavy bleeding, abdominal pain, decreased fetal movement, or a general decline in health.
Get tested for STIs if there’s any concern regarding exposure or if symptoms present, such as vaginal itching or unusual discharge.

Common Misconceptions About Miscarriage

The following are some widely held beliefs believed to increase the likelihood of miscarriage, despite evidence disproving their validity:

The mother’s emotional state, such as feeling stressed or depressed.
Experiencing a traumatic event during pregnancy.
Engaging in heavy lifting or strenuous activities during pregnancy.
Having sexual intercourse while pregnant.
Using contraceptive methods prior to the current pregnancy.
Experiencing morning sickness.
Participating in any form of exercise, including high-intensity activities like cycling and running, though consultation with a doctor is advised before beginning any new regimen.
Continuing professional work during pregnancy, regardless of whether it involves prolonged standing or sitting.
Flying during pregnancy.
Consuming spicy or heavily seasoned foods.

Video on the Causes of Miscarriage

To better understand the causes of miscarriage, please watch the following video: