"Miscarriage" is the lay term for the natural or accidental termination of a pregnancy at a stage where the embryo or the fetus is incapable of surviving.

The medical term for it is "abortion"; when the abortion is not deliberately induced, it is termed a "spontaneous abortion," so that is a synonym for "miscarriage." Medically, all pregnancy losses prior to 20 weeks gestation are considered miscarriages or abortions.
Miscarriages are the most common complication of pregnancy.



Miscarriages occur more often than most people think. About 25% of women will experience one in their lives.

Up to 78% of all conceptions may fail Template:Ref, most of which occur even before the woman knows she is pregnant. 15% of all confirmed pregnancies ends in a miscarriage.

After age 35, the risk of miscarriage increases considerably: 1 in 5 or 6. After 40, the risk increases to 1 in 3, and after 45 it is 1 in 2.

Medical aspects


Most such terminations occur very early in pregnancy, during the first trimester, and many people restrict the term "miscarriage" to early losses. Pregnancy losses in the second trimester are much less common.
Miscarriages frequently occur so early that the woman is not even aware that she is pregnant; these are preclinical pregnancy losses. Some women are prone to miscarry; the term "habitual abortion" is more and more replaced by "recurrent pregnancy loss" (RPL) and describes the condition where two or three consecutive pregnancies have terminated before 20 weeks gestation.


If a pregnant woman has vaginal bleeding, she is said to have a "threatened abortion", most patients with first trimester bleeding will be found to have a subchorionic hematoma and do well. In a minority such bleeding will progress to a pregnancy loss. With pain and opening of the cervix a woman is about to have an "inevitable abortion", which indicates that she has an absolute probability of miscarrying.

If some of the tissue remains in the uterus after a passing some tissue, this is called an "incomplete abortion". If the tissue in the uterus gets infected, it is a "septic abortion". In some cases the fetus dies, but the uterus does not expell the pregnancy:- this is called a "missed abortion". A "blighted ovum" pregnancy is a form of a miscarrage where the fetus either did not form, or died early, and the pregnancy consists only of trophoblastic tissue.

A specific form of a miscarriage is the ectopic pregnancy.


When looking for gross or microscopic pathologic symptoms of miscarriage, one looks for the products of conception.
Microscopically, these include villi, trophoblast, fetal parts, and background gestational changes in the endometrium. Cytogenetic studies show that half or more of first trimester pregnancy losses have abnormal chromosome arrangements.


Miscarriages can occur for many reasons, not all of which can be identified. They are most frequent during the first trimester. About 30% of fertilized eggs are actually lost before the woman knows she is pregnant and may only be noticeable by slightly more important blood loss.

First trimester losses are in many cases due to aneuploidy. A chromosomal abnormality occurs where the genetic material from the sperm and egg do not fuse together appropriately. The resulting baby does not develop properly. In other cases, a "blighted ovum" occurs, where the water bag and placenta develop but not the fetus.

Other possible but much less common causes include physical trauma, exposure to certain chemicals, infection, and immune factors. A number of studies have shown that cocaine and tobacco use are significant factors in spontaneous abortions among pregnant users, and that they contributes to a number of other threats to the health of the unborn.Template:Ref Second-hand smoke appears to present an equal danger to the fetus, as one study noted that "heavy paternal smoking increased the risk of early pregnancy loss."Template:Ref One of the rotating warnings that cigarettes are required to display notes that smoking can lead to "low fetal birth weight."

Pregnancy losses in the second trimester may be due to fetal abnormalities, uterine malformation, cervical problems, infection, trauma, immune factors, and medical disease.

Some conditions lead to recurrent pregnancy losses (recurrent spontaneous miscarriage or RSM). Often, doctors recommand an investigation after 3 or 4 losses and often find a cause for the recurrent miscarriages.

An uterine malformation (uterine septum) may cause about 15% of recurrent miscarriages. The uterine muscle is slightly malformed and the pregnancy cannot grow appropriately. The diagnosis is made by x-ray or ultrasound of the uterus.

Some unusual vaginal infections can cause recurrent miscarriages, although it appears that this is not common.

Rarely (about 3% of the time), a chromosomal problem of one or both partners can lead to recurrent pregnancy loss. This is called "balanced translocation". Patients which such a chromosomal problem are more likely to miscarriage, though they can also deliver normal babies.

Another cause of recurrent miscarriage is autoimmune problem. In this case antibodies circulating in the blood stream attack cells and tissues within the body. In some cases, antibodies cause blood clots in the placenta, which shuts off the blood supply to the developing fetus, causing a miscarriage. This can be diagnosed by blood tests and treated with low dose aspirin. These situations are likely to increase risks for the foetus and such pregnancies are hence considered high risk.

Other possible causes are hormonal abnormalities.
During pregnancy the corpus luteum produces the hormone progesterone necessary for maintaining the pregnancy during the first trimester. Some doctors consider that a luteal phase defect may cause pregnancy to stop. This occurs when insufficient amounts of progesterone is present to act on the lining of the uterus. This is diagnosed by tissue sampling (from the uterine lining) and treatment is usually hormonal.

Another potential cause for recurrent miscarriage is an allo-immune disorder, where the man and the woman have a lot of genetic material in common. This theory is extremely controversial.


Transvaginal ultrasonography has become the primary method of assessment of the health of an early pregnancy.


If a miscarriage is complete, and bleeding is contained and limited, only expectant management may be necessary. Excessive or prolonged bleeding needs medical attention. Often a dilation and curettage is indicated to remove tissue from the uterus. Tissue examination, including cytogenetic studies are helpful to determine the cause of the pregnancy loss. Febrile miscarriages need medical attention. Severe lower abdominal pain may indicate an ectopic pregnancy and needs medical attention.

Psychological aspects

Although a woman physically recovers from a miscarriage quickly, psychological recovery can take a long time. Women can differ a lot in this regard: some are 'over' it after a few months, others take more than a year.

What is the same for all women is that they will go through a process of grief. How short a time the child in her womb has lived does not matter for the feeling of loss. From the moment a woman becomes pregnant she starts to bond with her unborn child. When the child turns out not to be viable, dreams, fantasies and plans for the future are disturbed roughly.

Besides the feeling of loss, incomprehension from the environment is often important. Someone who hasn't gone through a miscarriage themselves can't know what it is and how upsetting it is. People around the woman may think that after weeks or maybe months, she will be over it. The pregnancy and miscarriage are hardly mentioned anymore in conversation, often too because the subject is too painful. This can make the woman feel isolated.

Interaction with pregnant women and newborn children is often also painful. Sometimes this makes the interaction with friends, acquaintances and family very difficult. Immediately after a miscarriage some women don't want to go out at all for fear of meeting acquaintances or pregnant women.

Some things a woman can do to deal with a miscarriage better are:

  • naming the child
  • keeping photos
  • arranging a funeral for the child
  • reading books on the subject
  • talking about it
  • finding others who have gone through a miscarriage
  • finding professional help: although it is a natural grieving process, it may take a long time. In such cases, a psychologist or grief counselor may be of help.


  1. Template:NoteRoberts CJ, Lowe CR. Where have all the conceptions gone? Lancet 1975;1:498-9
  2. Template:NoteNess, R., Grisso, J., Hirschinger, N., Markovic, N., Shaw, L., Day, N., and Kline, J. (1999). Cocaine and Tobacco Use and the Risk of Spontaneous Abortion. New England J. Med. 340:333-339; Oncken, C., Kranzler, H., O'Malley, P., Gendreau, P., Campbell, W. A. (2002). The Effect of Cigarette Smoking on Fetal Heart Rate Characteristics. Obstet Gynecol 99: 751-755.
  3. Template:Note Venners, S.A., X. Wang, C. Chen, L. Wang, D. Chen, W. Guang, A. Huang, L. Ryan, J. O'Connor, B. Lasley, J. Overstreet, A. Wilcox, and X. Xu. (2004). Paternal Smoking and Pregnancy Loss: A Prospective Study Using a Biomarker of Pregnancy Am J Epidemiol 159: 993-1001.

External links

See also: childbirth, stillbirth, premature birthsr:Абортус cs:Potrat de:Fehlgeburt fr:Fausse couche nl:Miskraam zh:流产


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