Spontaneous abortion

The spontaneous abortion or a natural abortion is the loss of an embryo or fetus for reasons not caused intentionally. It is thus distinguished from induced abortion . The term is strictly applied only when such loss occurs before the 20th week of pregnancy , one denominating from that time childbirth premature. Abortion can be subdivided into early (before week 12) and late (after week 12 and up to 20 weeks of gestation). Miscarriage can be retained , when nothing is eliminated , incomplete , when all products of gestation are not eliminated , or complete when everything is eliminated completely.

Other terms to refer to an early loss in pregnancy are:

  • Consummate abortion: all products of conception leave the body.
  • Incomplete abortion: only some of the products of conception leave the body.
  • Inevitable abortion: the symptoms can not be stopped and miscarriage occurs.
  • Abortion infected (septic): the lining of the uterus or uterus and any remaining conception products become infected.
  • Retained abortion: pregnancy is lost and the products of conception do not leave the body.


The most common cause is the death fetal anomalies by congenital fetus, often genetic , 2 especially trisomies (nonsexual) autosómicas. 3 In other cases it is due to abnormalities of the reproductive tract, or systemic diseases of the mother ( diabetes , nephritis , severe trauma), or infectious diseases ( Chagas disease , toxoplasmosis , brucellosis , syphilis , listeriosis , hepatitis B , AIDS ) and By traumatic events.


The natural rate of failure of gestations is very high, although most occur in the first weeks and in most cases the mother does not find out. It is estimated that one out of every five pregnancies detected ends in miscarriage in the first few weeks. The figure rises to over 30% in studies of pregnant women whose human chorionic gonadotropin hormone levels have declined after having confirmed pregnancy. 3

When a woman spontaneously aborts on three or more consecutive occasions, it is called a repeat abortion. The causes may be genetic in 50% of the cases, the antiphospholipid syndrome in 15% and other reasons such as uterine alterations and thrombophilia. 4

Among the proven risk factors are elevated age, systemic diseases, and previous repeated occurrence of miscarriages.

Symptoms and signs

The symptoms – ie signs perceived by the patient herself – most common are pain abdominal type colic or lumbar region; the bleeding vaginal with or without abdominal cramping pain or solid matter emission tissue or clots through the vagina. On the other hand some of these signs are frequent during the first months of gestation without necessarily having to follow abortion.

There are medical signs that can allow the specialist to detect a situation of risk of abortion.


Once observed signs of risk the recommendation is usually to restrict certain forms of activity, or even a complete rest. Likewise sexual abstinence is usually recommended in such cases. However, there are studies that say that rest has no beneficial effects and should be left to the patient’s choice. 5 6

If abortion occurs, there are usually obvious signs, first in the form of a reduction in the signs of pregnancy, but also in abnormal vaginal secretions, which must be evaluated, also to know if the abortion is complete or not.

If the abortion is not completed within a few weeks, surgery will be required to complete it artificially. Surgery can be replaced by a treatment with medication , but the side effects and the risk that the evacuation is not complete, forcing finally to resort to surgery, makes this option not always preferable.

The effects of a miscarriage usually go away by returning to the normal menstrual cycle and to a normal pregnancy probability, although a moratorium of one or two cycles is usually recommended before trying again.


The chances of miscarriage can be greatly limited by special attention from the mother and heightened medical surveillance, especially if they depend on physical limitations of the mother. The risk associated with systemic diseases is combated by treating them before the eventual pregnancy and monitoring the condition of the mother during the pregnancy.


  1. Back to top↑ «Loss of pregnancy » National Library of Medicine of the USA: National Institutes of Health . Retrieved on July 25, 2011
  2. Back to top↑ HASSOLD, T., CHEN, N., FUNKHOUSER, J., JOOSS, T., MANUEL, B., MATSUURA, J., et al. (1980). A cytogenetic study of 1000 spontaneous abortions. Annals of Human Genetics, 44 (2), 151-164. Doi: 10.1111 / j.1469-1809.1980.tb00955.x.
  3. ↑ Jump to:a b CRAIG P. GRIEBEL et al. «Management of Spontaneous Abortion» . Am Fam Physician (English) 72 : 1243-1250 . Consulted on December 3, 2009 .
  4. Back to top↑ Early pregnancy loss: Number 212 – September 1995 .. (1995). International Journal of Gynecology & Obstetrics, 51 (3), 278-285. Doi: 10.1016 / 0020-7292 (95) 80036-0.
  5. Volver arriba↑ Barclay, Laurie. «Bed Rest May Not Be Helpful for Threatened Miscarriage». Medscape Medical News (en inglés). Consultado el 29 de agosto de 2010.
  6. Back to top↑ German A, Althabe F, Belizán JM, Bergel E. «Bed rest during pregnancy for preventing miscarriage» . The Cochrane Database of Systematic Reviews 2010 (in English) . Accessed August 29, 2010 .