Types of Spontaneous Abortion

Spontaneous abortion, commonly called miscarriage, is pregnancy loss before 20 weeks of gestation. In Canada, the 20-week/500-g threshold also marks the vital-statistics boundary used to distinguish a miscarriage from a reportable stillbirth. Most sporadic first-trimester losses arise from fetal chromosomal aneuploidy present from conception, not from exercise, intercourse, work, or minor trauma. Recurrent losses require a broader differential, including antiphospholipid syndrome, uterine abnormalities, endocrine disease, and structural chromosome rearrangements in a parent. Classification depends on four clinical questions: Is the cervix open? Has tissue passed? Is the intrauterine pregnancy viable? Is infection present?