Miscarriage, also referred to as spontaneous abortion (SAB), is unfortunately very common. It occurs in 15-20% of all clinically recognized pregnancies (i.e.: early intrauterine pregnancy documented on ultrasound). Chemical pregnancy (when one has a positive pregnancy test that then turns negative without ever having a clinically recognized pregnancy) is not considered a miscarriage. Most miscarriage occurs before 12 weeks of gestation, with a large majority before 9 weeks.
What Causes Miscarriage?
There are several potential causes of miscarriage; however, most of the time we never know an exact reason.
- This composes the most common reason for miscarriage. When there is not a perfect or near perfect egg or sperm, then the formed embryo will most likely stop developing at some point early in the pregnancy. Miscarriage is the body’s way of protecting itself from investing energy in a pregnancy that may not produce a healthy baby. Because most often these genetic events are random and spontaneous (i.e.: they are unlikely to recur in the same exact way each time), we do not routinely examine the genetic make-up of a miscarriage, unless one has several miscarriages in a row.
- Increased maternal age would make miscarriage due to abnormal genetics more common.
- Health Causes
- Poorly controlled insulin-dependent diabetes
- Poorly controlled thyroid disease
- Severe and poorly controlled high blood pressure
- Chronic renal disease
- Infectious Causes
- A new infection with some viruses are thought to increase miscarriage rate (chicken pox, parvovirus, CMV, rubella)
- Abnormal uterine anatomy
- Some women are born with a uterus that is shaped in a way that does not allow a friendly environment for a pregnancy
- Some women have fibroids in a location that distorts the cavity of the uterus enough that it does not allow a normal environment for a pregnancy. Most fibroids do not affect a pregnancy.
- Thromboembolic Causes
- An essential and vital component of a successful pregnancy is the healthy growth and development of placenta. If there are microscopic blood clots in the vessels of the placenta, then the chance of successful pregnancy is lower (2x’s more likely for miscarriage).
- There are several genetic conditions that we sometimes check in women with recurrent miscarriage; however, the genetic thromboembolic disorders have not been proven to increase the risk of miscarriage significantly
- There is a non-genetic cause that we would assess in the setting of recurrent miscarriage. This is called anti-phospholipid antibody syndrome.
- Alcohol – Amount that leads to increase risk is unknown
- Tobacco- Greater than 14 cigarettes a day increases miscarriage rate to 2x’s more likely
- Caffeine- It is generally believed that the caffeine equivalent of 2 cups of coffee is safe
HOW IS MISCARRIAGE DIAGNOSED?
Diagnosis of miscarriage may be via ultrasound and or lab tests. Your physician will look for appropriate trends in the pregnancy both visually and by certain pregnancy-related hormone testing. Sometimes the pregnancy will start to pass on its own before the official diagnosis of miscarriage by ultrasound is made.
HOW IS A MISCARRIAGE MANAGED IF IT DOES NOT PASS ON ITS OWN?
- Some women (depending on gestational age) may be candidates for a trial of a medication called misoprostol (brand name is cytotec). This medicine works by causing the cervix to soften and open slightly and by leading to small uterine contractions.
- This has an 85% success rate.
- Please visit the following link for more information: Mifepristone + Misoprostol Instructions
- This is an outpatient procedure done at the hospital and is referred to as a D&E or a D&C. The surgeon gently dilates the cervix with metal rods and uses a suction device to evacuation the uterus.
- There is a very small risk of heavy bleeding or infection. Antibiotics are usually provided either before or after your surgery. There is an even smaller risk (1/1000) of the instruments poking a small hole in the wall of uterus. If this happens your surgeon may have to do laparoscopy to ensure no damage was done to surrounding organs like the bowel or the bladder.
- There is a 1% failure rate, meaning that a 2nd procedure would be necessary.
- Recovery is quick and one should anticipate vaginal bleeding for a few weeks.
WHEN CAN YOU TRY TO CONCEIVE AGAIN?
Ideally one would wait one full menstrual cycle to allow all of the uterine lining to reset and be ready for future implantation. One’s first period after a miscarriage may be heavier than normal and is usually 6-8 weeks after.
WHAT ARE MY CHANCES OF HAVING ANOTHER MISCARRIAGE?
Miscarriage rates do not increase until one has had 3 in a row. Depending on a woman’s health status, age, and other risk factors, we delay evaluation of some of the more rare causes of miscarriage until after 2 to 3 in a row. Thus, if you have had 1 to 2 miscarriages in a row, your chance of miscarriage is still 15-20% with the next pregnancy.