When an abortion (or miscarriage) takes place by itself, without any outside aid, we call it spontaneous abortion.
Some delicate ladies are perpetually liable to spontaneous abortion, before the third, or after the seventh, month of gestation.
spontaneous abortion, provided that proper medical care is given, rarely results in sepsis.
spontaneous abortion spon·ta·ne·ous abortion (spŏn-tā'nē-əs)
Abortion occurring naturally; miscarriage.