Early pregnancy loss may be defined as a loss within the first 12 completed weeks of pregnancy.1 Miscarriage is defined as the spontaneous loss of pregnancy before fetal viability. This term includes all pregnancy losses from conception until 24 weeks' gestation.2 Spontaneous miscarriages can occur in up to half of pregnancies before the first missed menstrual period, 10–20% of diagnosed pregnancies may result in early pregnancy loss.3 Early pregnancy loss accounts for over 50,000 admissions per year in the UK.4
Recurrent miscarriage refers to the loss of three or more pregnancies. Recurrent miscarriage may affect 1% of women.2 After three consecutive miscarriages, the risk of further miscarriage is approximately 40%. A woman may experience recurrent miscarriage after a successful pregnancy.
Early pregnancy loss may be attributed to chromosomal defects (with trisomy being the most common anomaly), uterine abnormality, infections and immunological factors.2 Advancing maternal age, poorly controlled diabetes and systemic lupus erythematosus are risk factors for miscarriage. Miscarriage is also associated with cigarette smoking, alcohol intake and illicit drug use.3