Spontaneous abortion, or miscarriage, is defined as a clinically recognized pregnancy loss before the 20th week of gestation [1,2]. The World Health Organization (WHO) defines it as expulsion or extraction of an embryo or fetus weighing 500 g or less. The term "fetus" will be used throughout this discussion, although the term "embryo" is the correct term at ≤10 weeks of gestation.
The management of spontaneous abortion, with a focus on the first trimester, is discussed here. The risk factors, clinical manifestations, diagnosis, and classification of spontaneous abortion are discussed separately. (See "Spontaneous abortion: Risk factors, etiology, clinical manifestations, and diagnostic evaluation".)
Preconceptual and prenatal counseling and care are the most important interventions for prevention of spontaneous abortion in women with no prior history of miscarriage. Use of pharmacologic therapy (eg, estrogen, vitamins) has not been found to be effective. Most miscarriages are not preventable, since chromosomal abnormalities account for approximately 50 percent of cases . (See "Spontaneous abortion: Risk factors, etiology, clinical manifestations, and diagnostic evaluation", section on 'Etiology'.)
Modifiable etiologies and risk factors for spontaneous abortion include :
●Maternal disease (eg, diabetes, thyroid disease, thrombophilia) – Preconceptual and prenatal care should include routine screening and optimal disease management for conditions that can result in miscarriage or other adverse effects to the fetus or mother during pregnancy.