A large majority (85%) of those who have had two miscarriages will conceive and carry normally afterward.The physical symptoms of a miscarriage vary according to the length of pregnancy, though most miscarriages cause pain or cramping. The size of blood clots and pregnancy tissue that are passed become larger with longer gestations. After 13 weeks gestation, there is a higher risk of placenta retention. Prevention
Prevention of a miscarriage can sometimes be accomplished by decreasing risk factors. This may include good prenatal care, avoiding drugs and alcohol, preventing infectious diseases, and avoiding x-rays. Identifying the cause of the miscarriage may help prevent future pregnancy loss, especially in cases of recurrent miscarriage. Often there is little a person can do to prevent a miscarriage. Vitamin supplementation before or during pregnancy has not been found to affect the risk of miscarriage. Progesterone has been shown to prevent miscarriage in women with 1) vaginal bleeding early in their current pregnancy and 2) a previous history of miscarriage. Non-modifiable risk factors
Preventing a miscarriage in subsequent pregnancies may be enhanced with assessments of:

Modifiable risk factors
Maintaining a healthy weight and good prenatal care can reduce the risk of miscarriage. Some risk factors can be minimized by avoiding the following:

Smoking
Cocaine use
Alcohol
Poor nutrition
Occupational exposure to agents that can cause miscarriage
Medications associated with miscarriage
Drug abuse

Management
Women who miscarry early in their pregnancy usually do not require any subsequent medical treatment but they can benefit from support and counseling.
These procedures are not associated with pregnancy loss during the second trimester but they are associated with miscarriages and birth defects in the first trimester. Miscarriage caused by invasive prenatal diagnosis (chorionic villus sampling (CVS) and amniocentesis) is rare (about 1%). Surgery
The effects of surgery on pregnancy are not well-known including the effects of bariatric surgery. Abdominal and pelvic surgery are not risk factors for miscarriage. Ovarian tumours and cysts that are removed have not been found to increase the risk of miscarriage. The exception to this is the removal of the corpus luteum from the ovary. This can cause fluctuations in the hormones necessary to maintain the pregnancy. Medications
There is no significant association between antidepressant medication exposure and spontaneous abortion. The risk of miscarriage is not likely decreased by discontinuing SSRIs prior to pregnancy. Some available data suggest that there is a small increased risk of miscarriage for women taking any antidepressant, though this risk becomes less statistically significant when excluding studies of poor quality.Medicines that increase the risk of miscarriage include:

retinoids
nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen
misoprostol
methotrexate
statins

Immunizations
Immunizations have not been found to cause miscarriage. Live vaccinations, like the MMR vaccine, can theoretically cause damage to the fetus as the live virus can cross the placenta and potentially increase the risk for miscarriage. Therefore, the Center for Disease Control (CDC) recommends against pregnant women receiving live vaccinations.