A miscarriage, also called a spontaneous abortion, 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.
Fertility may actually improve following a miscarriage. Some research found that fertility may be slightly enhanced for a couple of months after a miscarriage.
Researchers found that pregnancies conceived within 6 months of a miscarriage were more likely to be successful than those who waited before trying again.
- After a miscarriage, it is commonly recommended to wait to attempt to conceive again until a person is physically and emotionally ready.
- Waiting can ensure a woman’s body is ready to support a pregnancy and to reduce the chance of a repeat miscarriage.
- It is usually considered medically safe to conceive after two or three normal menstrual periods if tests or treatments for the cause of the miscarriage are not performed.
- However, some doctors may recommend couples wait six months to a year before attempting another pregnancy to come to terms with the loss.
While miscarriage does not impact fertility, three or more miscarriages may be a sign there is an underlying condition that is affecting fertility, such as:
- Blood clotting problems (antiphospholipid syndrome, also known as Hughes syndrome)
- Chromosomal abnormalities
- Cervical weakness
Conditions associated with recurrent miscarriage (though they may not cause it) include:
- Infections, such as sexually transmitted diseases (STDs), toxoplasmosis, rubella, and listeria
- Uterine abnormalities
- Uncontrolled diabetes
- Unmanaged thyroid problems
- Polycystic ovary syndrome (PCOS)
- Immune problems
- Fibroids
Recurrent miscarriages should be evaluated by a fertility specialist.
What Are Symptoms of Miscarriage?
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
- Passage of pregnancy tissue
- Mild to severe back pain
- Weight loss
- Painful contractions occurring every 5-20 minutes
If you are pregnant and have any signs of a miscarriage, see your doctor right away.
What Causes Miscarriage?
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
- Intimate partner violence
- Gunshot wounds
Risk factors for miscarriage include:
- Increasing maternal age, over 35 years
- Medical conditions
- Prior miscarriage
- Obesity
- Diabetes
- Thyroid disease
- Endocrine disorders
- Infection
- Acute and chronic stress
- Inheritable thrombophilias
- Pregnancy with intrauterine device (IUD) in place
- Subchorionic hematoma
- Medication and/or substance use
- Smoking
- Alcohol
- Caffeine
- Certain nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen and diclofenac
- Environmental exposures
- Race and ethnicity
- Women of color have an increased risk compared to white women
How Is Miscarriage Diagnosed?
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
What Is the Treatment for Miscarriage?
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 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)
- If miscarriage occurs with heavy bleeding or signs of infection, surgical treatment is recommended
From 
Women's Health Resources
https://www.uptodate.com/contents/overview-of-pregnancy-termination?search=abortion&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
https://www.uptodate.com/contents/pregnancy-loss-miscarriage-risk-factors-etiology-clinical-manifestations-and-diagnostic-evaluation?search=miscarriage&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2
https://www.uptodate.com/contents/spontaneous-abortion-management?search=miscarriage&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
https://americanpregnancy.org/healthy-pregnancy/pregnancy-complications/signs-of-miscarriage-916
https://americanpregnancy.org/getting-pregnant/pregnancy-loss/pregnancy-after-miscarriage/
https://www.babycentre.co.uk/x546737/ive-had-a-miscarriage-will-this-affect-my-fertility
https://www.tommys.org/about-us/charity-news/tommys-professor-shennan-new-study