Miscarriage (Early Pregnancy Loss)
Basics
Basics
Basics
Description
Description
Description
- Miscarriage, also known as early pregnancy loss (EPL) or spontaneous abortion (SAb), is the failure or loss of a pregnancy before 13 weeks’ gestational age (WGA).
- Related terms
- Anembryonic gestation: gestational sac on ultrasound (US) without visible embryo after 6 WGA
- Complete abortion: entire contents of uterus expelled
- Ectopic pregnancy: pregnancy outside the uterus
- Embryonic or fetal demise: cervix closed; embryo or fetus present in the uterus without cardiac activity
- Incomplete abortion: abortion with retained products of conception, generally placental tissue
- Induced or therapeutic abortion: evacuation of uterine contents or products of conception medically or surgically
- Inevitable abortion: cervical dilatation or rupture of membranes in the presence of vaginal bleeding
- Recurrent abortion: ≥3 consecutive pregnancy losses at <15 WGA
- Threatened abortion: vaginal bleeding in the 1st trimester of pregnancy
- Septic abortion: a spontaneous or therapeutic abortion complicated by pelvic infection; common complication of illegally performed induced abortions
- Synonym(s): spontaneous abortion
- Missed abortion and blighted ovum are used less frequently in favor of terms representing the sonographic diagnosis.
Epidemiology
Epidemiology
Epidemiology
Predominant age: increases with advancing age, especially >35 years; at age 40 years, the loss rate is twice that of age 20 years.
Incidence
- Threatened abortion (1st-trimester bleeding) occurs in 20–25% of clinical pregnancies.
- Between 10% and 15% of all clinically recognized pregnancies end in EPL, with 80% of these occurring within 12 weeks after last menstrual period (LMP) (1).
- When both clinical and biochemical (β-hCG detected) pregnancies are considered, about 30% of pregnancies end in EPL.
- One in four women will have an EPL during her lifetime (1).
Etiology and Pathophysiology
Etiology and Pathophysiology
Etiology and Pathophysiology
- Chromosomal anomalies (50% of cases)
- Congenital anomalies
- Trauma
- Maternal factors: uterine abnormalities, infection (toxoplasma, other viruses, rubella, cytomegalovirus, herpesvirus), maternal endocrine disorders, hypercoagulable state
Genetics
Approximately 50% of 1st-trimester EPLs have significant chromosomal anomalies, with 50% of these being autosomal trisomies and the remainder being triploidy, tetraploidy, or 45X monosomies.
Risk Factors
Risk Factors
Risk Factors
Most cases of EPL occur in patients without identifiable risk factors; however, risk factors include the following:
- Chromosomal abnormalities
- Advancing maternal age
- Uterine abnormalities
- Maternal chronic disease (antiphospholipid antibodies, uncontrolled diabetes mellitus, polycystic ovarian syndrome, obesity, hypertension, thyroid disease, renal disease)
- Other possible contributing factors include smoking, alcohol, cocaine use, infection, and luteal phase defect.
General Prevention
General Prevention
General Prevention
- Insufficient evidence supports the use of aspirin and/or other anticoagulants, bed rest, hCG, immunotherapy, uterine muscle relaxants, or vitamins for general prevention of EPL, before or after threatened abortion is diagnosed.
- By the time hemorrhage begins, half of pregnancies complicated by threatened abortion already have no fetal cardiac activity.
In threatened abortion, oral progestogens may reduce the risk of EPL (RR 0.73, 95% CI 0.59–0.92) and increase the rate of live birth (RR 1.07, 95% CI 1.00–1.15) (
2)[
B].
- Antiphospholipid syndrome: The combination of unfractionated heparin and aspirin reduces risk of EPL in women with antiphospholipid antibodies and a history of recurrent abortion (3)[C].
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