Miscarriage refers to the premature end of a pregnancy before the developing baby is able to survive outside the womb. Miscarriage can occur during the first or second trimester, before 20 weeks. Most occur in the first 12 weeks of pregnancy. They often are unexpected and isolated events. About 15%-20% of recognized pregnancies end this way.
Fetus in First Trimester
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Miscarriages often occur for the following reasons:
- Chromosomal abnormalities (common cause)
- Abnormalities in the uterine tract (eg, fibroids)
- Hormonal problems (eg, not having enough progesterone, a female hormone needed to support pregnancy)
- Factors related to the immune system (eg, may cause blood-clotting problems or rejection of the fetus)
In some cases, the cause is unknown.
Last reviewedSeptember 2013by Andrea Chisholm, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.