A miscarriage is the loss of a pregnancy during the first 20 weeks. (After 20 weeks, pregnancy loss is known as a stillbirth.) Overall, miscarriage affects up to 1 out of 4 women who become pregnant at some point in their lifetime.1
The risk of miscarriage increases as a woman ages:1

Other factors also associated with an increased risk of miscarriage include:
1 Schieve LA, et al. (2003). Spontaneous abortion among pregnancies conceived using assisted reproductive technology in the United States. Obstetrics and Gynecology, 101(5, Part 1): 959–967.
| By | Healthwise Staff |
| Primary Medical Reviewer | Sarah Marshall, MD - Family Medicine |
| Specialist Medical Reviewer | Femi Olatunbosun, MB, FRCSC - Obstetrics and Gynecology |
| Last Revised | December 7, 2011 |