Miscarriage: Encyclopedia II - Miscarriage - Causes

Miscarriage - Causes

Miscarriages can occur for many reasons, not all of which can be identified. They are most frequent during the first trimester. About 30% of fertilized eggs are actually lost before the woman knows she is pregnant and may only be noticeable by slightly more important blood loss.

First trimester losses are most commonly caused by one time non-repeating genetic problems. This can be the result of an abnormal sperm, and abnormal ovum or an abnormal combination of the egg and sperm. The resulting baby does not develop properly and in some cases, the development of the embryo stops before it can be seen, a "blighted ovum". It is important to keep in mind that these are non-repeating genetic defects. Therefore, women who have had one miscarriage do not have a higher risk of having a second miscarriage.

Other possible but much less common causes include physical trauma, exposure to certain chemicals, infection, and immune factors. A number of studies have examined lifestyle factors. Thus obesity, high caffeine intake (> 300 mg/day), alcohol consumption, and use of NSAIDs have all been linked to higher miscarriage rates in general. Also women undergoing fertility therapy tend to have higher miscarriage rates.

In the US, smoking label warnings must be displayed to inform women that smoking can lead to "low birth weights"^{[5] [6]} .

Pregnancy losses in the second trimester may be due to fetal abnormalities, uterine malformation, cervical problems, infection, trauma, immune factors, and medical disease.

Adapted from the Wikipedia article "Causes", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki