Spontaneous Abortion


The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is a spontaneous abortion?

A spontaneous abortion, commonly known as a miscarriage, is the termination of a pregnancy, without outside intervention, before 20 gestational weeks. From 20 weeks onward, the spontaneous termination of a pregnancy without the survival of the fetus is known as a stillbirth (if the baby survives, it is called preterm birth). Both spontaneous abortion and stillbirth differ from induced abortion, in which the pregnancy is terminated deliberately without the survival of the fetus. The term spontaneous abortion encompasses inevitable abortion, in which there is bleeding, and the cervical os (the lower part of the cervix, leading to the vagina) is open, or the embryo or fetus is otherwise nonviable, but it has not yet been expelled. It also encompasses missed abortion (embryo/fetus is not viable, but no expulsion of products of conception has been noticed), incomplete abortion (part of the embryo/fetus, placenta, or membranes have been expelled, but part remains in the uterus), complete abortion (body has expelled all products of conception), and septic abortion (all or some products of conception remain in the uterus where they cause an infection). Additionally, a situation called a threatened abortion often is listed with the other conditions, but it is not a spontaneous abortion. Rather, a threatened abortion means that there is bleeding, indicating that the situation could evolve into a spontaneous abortion, but the cervical os is closed, and the fate of the embryo or fetus is not yet known. 

How common is a spontaneous abortion during pregnancy?

The reported incidence of spontaneous abortion generally ranges from 10 to 20 percent.3 However, this is based on pregnancies that have been identified. Based on laboratory studies, on studies of human fertility, on reports of bleeding in women within weeks of missed periods, and on the current understanding of the genetics and embryology of early pregnancy, it is thought that spontaneous abortion is the most common outcome of conception. Probably, this is because most fertilizations result in zygotes that have lethal chromosomal abnormalities.

In most cases, spontaneous abortion occurs before the woman even recognizes that she is pregnant. Spontaneous abortion is a way for the body to clear out products of conception that either would not produce a viable fetus or would produce a neonate with severe, often non-survivable, deformities. Nevertheless, some factors increase the likelihood of spontaneous abortion, such as age older than 35 years, problems with your uterus or cervix (such as cervical incompetence the cervix cannot stay closed tightly), being underweight or overweight, chronic disease such as diabetes, smoking, alcohol, cocaine, and other illicit drugs, and, of course, a history of previous spontaneous abortions. Additionally, invasive prenatal tests, namely amniocentesis and chorionic villus sampling (CVS), increase the risk slightly, although these tests are fairly safe with modern ultrasonography guidance when conducted by experienced operators. As for caffeine, every now and then, a study is published suggesting that it does or does not trigger spontaneous abortion of embryos that have normal chromosomes. What is clear, however, is that typical doses of caffeine, such as what you ingest in two or three cups of coffee per day, are not enough to cause a spontaneous abortion.

How is a spontaneous abortion diagnosed?

In most cases, diagnosis involves testing your blood for the concentration of the pregnancy hormone beta-human chorionic gonadotropin (ß-hCG), ultrasonography, and examination of the cervical os. If you experience bleeding and the cervical os is closed, this could be considered a threatened abortion, but if ultrasonography does not identify a heartbeat and/or if your ß-hCG level is too low for the amount of time that you have been pregnant, or does not increase appropriately over time, then it becomes an inevitable abortion. If you suffer bleeding and the cervical os is open, it is a spontaneous abortion, but the type of spontaneous abortion depends on what remains in the uterus.

Does a spontaneous abortion cause problems during pregnancy?

Spontaneous abortion ends the pregnancy, but you suffer bleeding and often a lot of pain, although there may not be pain if the abortion occurs early in pregnancy. The later the abortion occurs in pregnancy, the more likely you are to suffer other complications, such as significant blood loss (which can lead to your blood pressure dropping) and infection (septic abortion).

Does a spontaneous abortion cause problems for the baby?

Spontaneous abortion ends the pregnancy, and there is no longer a viable embryo or fetus, so there is no baby.

What to consider about taking medications when you are pregnant or breastfeeding:

  • The risks to yourself and your baby if you do not treat a spontaneous abortion
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat a spontaneous abortion?

Women who suffer an incomplete abortion, or a missed abortion, benefit from treatment with misoprostol, a medication that stimulates expulsion of products of conception remaining in the uterus. If you suffer a septic abortion, then you will be treated with a regimen of antibiotic medication.

Who should NOT stop taking medication for a spontaneous abortion?

Misoprostol is given as only 1 to 3 doses, depending on your needs, so there is no long regimen that you can stop. If you are taking antibiotics for a septic abortion, then you must complete your prescribed regimen, although you should report side effects to your doctor.

What should I know about choosing a medication for my spontaneous abortion?

It is important to stay in communication with your health care provider as the release of new studies over time can change the outlook on the role of specific medications during pregnancy.

You may find Pregistrys expert reports about the medications to treat this condition here. Additional information can also be found in the sources listed below.

What should I know about taking a medication for my spontaneous abortion when I am breastfeeding?

Spontaneous abortion means that you do not have a baby, so there is no issue related to breastfeeding.

What alternative therapies besides medications can I use to treat my spontaneous abortion?

If a spontaneous abortion appears to be complete – if ultrasonography reveals that all products of conception have been expelled, there is little to do other than to have you rest and return to be examined. If the embryo is not viable early in the pregnancy and ultrasound reveals that it has not been expelled, then you are suffering from an inevitable abortion, in which case the plan is expectant management, meaning that you wait for nature to take its course and expel the embryo and other materials. If it is later in pregnancy than a minor surgical procedure will be needed, called dilation and curettage (D&C).  

What can I do for myself if I have a spontaneous abortion?

Follow the instructions of your physician. If this is the first time that this has happened to you, be assured that spontaneous abortion is always the most likely outcome of conception, but in
this case, the pregnancy advanced far enough so that you were aware of it and enough so that it caused extensive bleeding and pain. Obstetricians generally recommend that you wait at least three months, but then recommend that you try to get pregnant again. If you have suffered repeated spontaneous abortions, then you should be evaluated to assess the underlying cause.

Resources for spontaneous abortion in pregnancy:

For more information about spontaneous abortion during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or contact the following organizations:

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General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

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