Threatened Miscarriage Causes

Although the actual cause of the miscarriage is frequently unclear, the most common reasons include the following:

• An abnormal fetus is almost always the cause of miscarriages during the first 3 months of pregnancy (first trimester). Problems in the genes cause an abnormal fetus and are found in more than half of miscarried fetuses. The risk of defective genes increases with the woman's age.

• Miscarriage during the fourth through sixth months of pregnancy (second trimester) is usually related to an abnormality in the mother rather than in the fetus.
  
  
  • Chronic illnesses, including diabetes, severe high blood pressure, kidney disease, lupus, and underactive or overactive thyroid gland, are frequent causes of a miscarriage. Prenatal care is important because it screens for some of these diseases.
  
  
  
  • Inadequate ovarian hormone production is one of the most common causes of a miscarriage.
  
  
  
  • Acute infections, including German measles, CMV (cytomegalovirus), mycoplasma ("walking" pneumonia) and other unusual germs, and severe emotional shock, can also cause miscarriage.
  
  
  
  • Diseases and abnormalities of the internal female organs can also cause miscarriage. Some examples are an abnormal womb, fibroids, poor muscle tone in the mouth of the womb, abnormal growth of the placenta (also called the afterbirth), and carrying too many babies for your system.
  
  
  
  • Other factors, especially certain drugs, including excessive caffeine, alcohol, tobacco, and cocaine, may be the cause.