An early miscarriage is the spontaneous loss of pregnancy during the first 20 weeks of gestation. It can also be called a spontaneous abortion (fig. 1).
Early miscarriage is very common. As many as 30% of women will experience one, usually before they even miss a period, or realize they are pregnant. Most early miscarriages are a result of a developing fetus that is unhealthy and has little chance of surviving to the end of pregnancy.
Some known causes include:
- Chromosomal abnormalities. Studies show that 50% to 60% of all miscarriages are caused by too little or too many chromosomes in the fetus. Of these cases about half are caused by Trisomy 21, also referred to as Down's Syndrome.
- Low progesterone levels. The hormone progesterone is necessary for maintaining a healthy pregnancy. Insufficient levels may result in miscarriage. Early in pregnancy the progesterone is made by the small cyst in the ovary called the corpus luteum. After about nine to 10 weeks the placenta should be producing enough progesterone to support the pregnancy. Low progesterone that causes miscarriage is usually thought to be from inadequate production from the corpus luteum. Progesterone medication is safe and relatively inexpensive, but studies proving its effectiveness have not been conclusive.
- Infections and diseases. Many bacterial and viral infections can contribute to a miscarriage, including viral infections such the cytomegalic virus, bacterial infections such as chlamydia, mycoplasma, ureaplasma, and streptococcus, or in rare cases parasitic infection such as toxoplasmosis. Disease, such as undiagnosed diabetes, may also cause a miscarriage.
- Age of the mother. The rate of miscarriage increases with the age of the mother. Around half of all pregnancies in women over 40 end in miscarriage.
- Other possible causes. Chronic illnesses, exposure to environmental toxins (such as certain metals), and stress. Examples include thyroid abnormalities (either overactive or underactive thyroid), poorly controlled diabetes mellitus, or intrauterine adhesions (most commonly caused by previous infections or dilatation and curettages.) High dose X-irradiation and chemotherapy are known toxins that can cause pregnancy loss. Industry employees working with chemicals such as with dyes, metals, solvents, or chemical production plants are at greater risk. Maternal stresses and heavy use of tobacco, caffeine, alcohol, and drugs can also be factors.
- Autoimmune diseases. The presence of certain complex antibodies such as the lupus anticoagulant and the anticardiolipin antibodies can cause miscarriages. These factors are not well understood, and there is no agreed upon effective treatment.
Women often unnecessarily blame themselves for having a miscarriage. It is important to remember that the fetus probably would not have survived the pregnancy anyway. And keep in mind that having one miscarriage does not necessarily mean having another. The chances are very high that you'll carry your next baby to full term.
How Do I Know I Have It?
If you are pregnant and have any of these symptoms, call your health-care provider immediately:
- Vaginal bleeding. Especially heavy bleeding with passage of blood clots.
- Abdominal pain. Severe or persistent pain in the pelvis or lower back.
- Blood clots. Grayish matter may pass as the miscarriage begins. This is the embryo and placenta. If you do pass tissue at home your health care provider will likely instruct you to collect the tissue and place it in a clean jar to bring in for medical inspection.
- The early ending of morning sickness symptoms and loss of breast tenderness. Many women experience these symptoms in the first trimester, but by the beginning of the fourth month of pregnancy, they commonly subside. When women experience a loss of these symptoms earlier than the second trimester, and if symptoms subside abruptly, miscarriage may have occurred. The technical term for this occurrence is a "missed abortion."
Your health-care provider will listen for a fetal heartbeat and perform a pelvic exam. If a heartbeat is not heard and your cervix is dilated, or widened, or if your membranes have ruptured, then most likely a miscarriage is in progress, or has already happened. This may be termed an "inevitable miscarriage." If a fetal heartbeat is detected and your uterus is still enlarged, you may have suffered a threatened miscarriage. In this case, you will have vaginal bleeding but the fetus is still alive. These may also be symptoms of ectopic pregnancy.
An ultrasound exam may also be administered; those performed transvaginally are the most accurate. This test emits high-frequency sound waves that penetrate the uterus to reveal an image of the fetus on a monitor. If no image of the fetus is seen or if you can see fetal tissue traveling through the dilated cervix, then you may have had a miscarriage, or are in the process of one. If the fetus looks intact and your uterus is still enlarged, then you may have suffered a threatened miscarriage. Some women do not experience any symptoms. When this happens, the miscarriage may go undetected for several weeks, until the next prenatal visit. If a fetal heartbeat is not heard after eight to 10 weeks' gestation and there is no sign of uterine growth, then a miscarriage probably took place.
Many miscarriages happen before a woman knows she's pregnant. Miscarriages can be mistaken for periods that are unusually heavy and severe. If you have any concerns about your last period, talk to your health-care provider.
How Is It Treated?
Surgery is not necessary if the fetus and placenta are completely expelled from the uterus. Modern management has determined that this may be both a safe and economical approach to a spontaneous miscarriage. But if only part of the fetus and placenta are expelled or, none at all, one of two procedures may be suggested:
- D & C (dilation and curettage). The cervix is dilated or widened and a curette is used to scrape the remaining tissue from the lining of the uterus.
- Vacuum aspiration. A mechanical pump is used to suction the remaining tissue out of the uterus.
Bleeding may continue for several weeks after a miscarriage and change in color from bright red to pink. If you undergo the suction procedure, you may also experience abdominal cramping.
If the bleeding gets heavier after a few weeks instead of decreasing, contact your health-care provider. If a fever develops, or if vaginal discharge has a strange or unpleasant odor, inform your doctor. Avoid intercourse, douching, or using tampons for at least two weeks and then gradually resume normal activities, such as exercise.
How Can I Prevent It?
It is difficult to prevent an early miscarriage. If you know you are pregnant, make sure you get proper prenatal care and talk to your health-care provider about such crucial matters like an appropriate diet and the exact nutritional supplements to take.
After a threatened miscarriage, rest in bed for at least a day and avoid intercourse for a few weeks. Most likely you will carry your baby to term. Remember, it's very normal for women to bleed in early pregnancy, and it's certainly not always an indication that the fetus is unhealthy or that you are having a miscarriage. In fact, some women bleed throughout their pregnancy. It should be brought to your health care provider's attention as bleeding can be associated with other medical problems such as uterine fibroids, abnormal placental implantation, chronic abruptio (relatively rare). Talk to your health-care provider about any concerns you have.
Frequently Asked Questions
Q: I've already had one miscarriage. Does this mean I'm more likely to have another one?
A: Having one miscarriage does not increase your chances of having another. If you have had only one prior miscarriage, the rate of spontaneous abortion in a subsequent pregnancy is similar to the overall rate in the general population.
Q: After my miscarriage, how long should I wait before I try to conceive again?
A: It is suggested that you wait two normal periods (around eight weeks) before you try to conceive again. Ovulation can resume as early as two weeks after a miscarriage, so you should use effective contraception immediately.
Q: Can being too active cause a miscarriage?
A: No. Working, exercise, and sexual activity do not increase the risk of miscarriage. Also, miscarriages rarely occur because of stress or trauma.
Q: I have had two miscarriages. Should I have special testing?
A: Since most miscarriages are caused by a defect of the particular fertilized egg, most experts do not recommend special testing until you have had three miscarriages. At that point it is termed "recurrent" or "habitual" miscarriage and further testing may be needed. Studies have shown that after a woman experienced three consecutive miscarriages, her chance of having a subsequent spontaneous abortion is nearly 50%.
Review Date: June 29, 2001
Reviewed By: Peter Chen, M.D., Obstetrics and Gynecology, University of
Pennsylvania School of Medicine. Review provided by VeriMed Healthcare
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