What Are Abortion and Miscarriage?

Abortion refers to the termination of a pregnancy, which may happen naturally or with medical intervention. A miscarriage is known as a "spontaneous abortion."

Abortion is a term that refers to the termination of a pregnancy. This can occur with medical intervention such as medications or surgical procedures or it can occur on its own. 

A miscarriage is called a spontaneous abortion, and refers to a pregnancy loss before the 20th week of gestation or the expulsion an embryo or fetus weighing 500 g or less. Miscarriage at this stage occurs in about 31% of pregnancies.

Some women may have no symptoms of miscarriage and it is discovered on a routine ultrasound in early pregnancy.

When symptoms of miscarriage occur, they may include:

• Vaginal bleeding 
  • May be light or heavy
  • Bleeding can depend on how far along you are in the pregnancy
• Abdominal cramping 
• Sudden loss or reduction of pregnancy symptoms, such as decreased breast tenderness and/or nausea and vomiting
• Passage of pregnancy tissue
• Mild to severe back pain
• Weight loss
• Painful contractions that occur every 5-20 minutes

If you are pregnant and have any signs of a miscarriage, see your doctor right away.

Causes of miscarriage include:

• Chromosomal abnormalities
  • Present in up to 70% of pregnancy losses before 20 weeks
• Maternal anatomical abnormalities
  • Uterine fibroids (leiomyomas)
  • Endometrial polyps
  • Uterine adhesions
  • Uterine septum
• Trauma
  • Penetrating injuries
  • Gunshot wounds
  • Intimate partner violence

Risk factors for miscarriage include:

• Increasing maternal age, over 35 years
• Medical conditions
  • Prior miscarriage
  • Endocrine disorders
  • Obesity
  • Infection
  • Diabetes
  • Thyroid disease
  • Acute and chronic stress
  • Inheritable thrombophilias
  • Pregnancy with intrauterine device (IUD) in place
  • Subchorionic hematoma 
• Medication and/or substance use
  • Certain nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen and diclofenac
  • Smoking
  • Caffeine
  • Alcohol
• Environmental exposures
  • Ionizing radiation
  • Lead or arsenic exposure
  • Air pollution
• Race and ethnicity
  • Women of color have an increased risk of miscarriage compared to white women 

Once a pregnancy has been diagnosed, a miscarriage may be diagnosed by a doctor with:

• Pelvic exam
• Ultrasound
• Blood tests
  • Human chorionic gonadotropin (HCG)
• Tests on tissue you may have passed to confirm a miscarriage
• Chromosomal tests if you have had previous miscarriages to determine if your chromosomes or your partner’s chromosomes play a role

If an ultrasound confirms a miscarriage and determines the embryo is no longer viable or has not fully formed, there are several treatment options:

• Expectant management
  • Let the miscarriage progress naturally and allow the embryo to pass on its own
  • This may take up to 4 weeks and can be difficult emotionally
  • If the embryo does not pass on its own within 4 weeks, medical or surgical intervention is recommended because of the risk of infections, potential for loss of the uterus, or threat to the mother’s life
• Medical treatment
  • Medications can be given to help the body expel the pregnancy tissue
  • For most women, these medications work within 24 hours
    • Mifepristone (Mifeprex) followed by misoprostol (Cytotec)
    • Misoprostol (Cytotec) alone
• Surgical treatment
  • Suction dilation and curettage (D&C) is a procedure in which the cervix is dilated and tissue from the inside of the uterus is removed
  • If miscarriage occurs with heavy bleeding or signs of infection, surgical treatment is recommended