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What Happens During a Miscarriage?

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Updated February 14, 2008

Question: What Happens During a Miscarriage?

Exactly what happens during a miscarriage varies by the cause and type of miscarriage.

Answer:

In most first trimester miscarriages, the baby stops developing at some point early in the pregnancy. The woman's body then recognizes that the pregnancy is not viable and begins to shed the uterine lining, leading to mild cramping alongside vaginal bleeding -- the most common signs of miscarriage.

The woman's body does not always recognize immediately that the pregnancy is not viable, however, and weeks can pass before miscarriage symptoms appear. If an ultrasound takes place during this time period, the doctor will usually diagnose a missed miscarriage or a blighted ovum (depending on the exact circumstances and assuming the doctor is confident in the dating of the pregnancy).

Threatened Miscarriages

Most of the time, the baby's heart has stopped beating before the miscarriage symptoms appear -- but in some cases, the heartbeat may still be detectable when the miscarriage symptoms appear. If the woman is still in the first trimester, this will most likely be diagnosed as a threatened miscarriage.

Sometimes the bleeding stops in these cases and the pregnancy is still viable, meaning the bleeding was for some other reason than a miscarriage (but if the heartbeat has stopped after having previously been detected, the pregnancy is definitely no longer viable). If a miscarriage does occur, what happens is that the body appears to trigger the uterine lining to shed for some reason. Doctors do not understand why this happens and usually cannot stop the process if it happens in the first trimester -- although they may advise bed rest as a precaution.

Second Trimester Miscarriages

Early second trimester miscarriages can happen the same way as first trimester miscarriages -- the baby's heart stops and the woman begins to have miscarriage symptoms, but the woman might require a D & E to treat the miscarriage rather than waiting for the process to happen naturally. Late second trimester miscarriages might mean that the baby dies and the woman no longer feels any movement; after 20 weeks this pregnancy loss is technically a stillbirth.

In the second trimester, miscarriage can also occur because of cervical insufficiency or preterm labor. With preterm labor in the second trimester, doctors can sometimes stop labor with medical intervention, such as by prescribing certain drugs along with bedrest, if the signs are caught early enough.

A miscarriage because of cervical insufficiency might occur without any warning. What happens in this type of miscarriage is that the cervix can slowly thin and then the baby can be born too prematurely to survive, even if the pregnancy was otherwise viable.

Doctors can treat cervical insufficiency with a cervical cerclage, but only if the condition is detected early. Because cervical insufficiency is not common, doctors do not routinely screen women who do not have pre-existing risk factors (such as a prior loss because of the condition or a known congenital uterine malformation).

Source:

American Pregnancy Association, "Miscarriage." July 2007. Accessed 8 Feb 2008.

  1. About.com
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  3. Miscarriage / Pregnancy Loss
  4. Symptoms & Diagnosis
  5. Diagnosing Pregnancy Loss
  6. What Happens During a Miscarriage - What is Happening During a Miscarriage

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