Indeed, spontaneous abortion due to an error of nature it corrects itself by expelling the egg. The causes of miscarriages are numerous:
It may be that a woman's eggs are not in good condition when released during ovulation.
A normal egg can be fertilized by sperm damage.
A normal embryo can be damaged by the ill health of the mother, malnutrition, or because of medications she takes.
Abnormalities in the uterus.

How to manifest a miscarriage?

The threat of miscarriage is manifested by some bleeding suddenly and often accompanied by pain in the abdomen. However, sometimes a pregnant woman to lose a little blood during the first two or three months of pregnancy. In all cases, consult your doctor is essential to find the meaning of this loss of blood. Your doctor will do an ultrasound to clarify the normal or non-pregnancy by the appearance of the egg and its volume.
The doctor may request a determination of the hormone of pregnancy (Beta HCG) to determine whether this hormone is secreted at a normal rate or not.

What should I do ?

If the threat is false in connection with a known cause. Your doctor will prescribe the appropriate treatment. Otherwise, wait to see how events will turn: miscarriage or not. This may take a few days time to do another ultrasound to make an accurate diagnosis of the causes of blood loss.

What will happen ?

Sometimes the bleeding and reduce the dosage of the hormone of pregnancy (Beta HCG) increases gradually. An ultrasound will confirm that the evolution of the pregnancy continues. These cases are often due to a partial placental abruption. The physician determine when the threat of abortion is excluded and when you can resume your normal activities.
If the bleeding is quite heavy and accompanied by colic in the abdomen. These are the contractions of the uterus that occur for the expulsion of the egg. You need to quickly check the doctor or midwife.
If severe bleeding: an emergency hospitalization in a hospital or clinic is required.