DiseaseDisorder infobox |
Name = Habitual abortion |
ICD10 = N96 |
ICD9 = 629.9 |
Habitual abortion or recurrent pregnancy loss (RPL) is the occurrence of repeated pregnancy|pregnancies that end in miscarriage of the fetus, usually before 20 weeks of gestation. RPL affects about 0.34%ref|RCOG2003 of women who conceive.
Habitual abortion (recurrent pregnancy loss or recurrent miscarriage) is the occurrence of 3 consecutive spontaneous miscarriages (spontaneous abortions). The majority (85%) of women who have had two miscarriages will conceive and carry normally afterwards, so statistically the occurrence of three abortions at 0.34%ref|RCOG2003 is regarded as “habitual”.
There are various causes for habitual abortions, and some are treatable. Some couples never have a cause identified, often after extensive investigations.ref|RCOG2003
An uterine malformation is considered to cause about 15% of recurrent miscarriages. The most common abnormality is a uterine septum, a partition of the uterine cavity. The diagnosis is made by x-ray or ultrasound of the uterus. Also uterine leiomyomata could result to pregnancy loss. In the second trimester a weak cervix can become a recurrent problem.
An important example is the increased risk of abortion in women with thrombophilia (propensity for thrombosis|blood clots). Recent studies confirm that anticoagulant medication may improve the chances of carrying pregnancy to term. It explains about 15% of recurrent miscarriages.
A Chromosomal translocation|balanced translocation or Robertsonian translocation in one of the partners leads to unviable fetuses that are aborted spontaneously. This explains why a karyogram is often performed in both partners if a woman has suffered repeated abortions.
About 3% of the time a chromosomal problem of one or both partners can lead to recurrent pregnancy loss. Patients which such a chromosomal problem are more likely to miscarriage, they can also deliver normal or abnormal babies.
Women with thyroid disorders, both hypo- or hyperactivity, have are at increased risk for pregnancy losses. Unrecognized or poorly treated diabetes mellitus leads to increased miscarriages. Women with polycystic ovary syndrome also have higher loss rates possibly related to hyperinsulinemia or excess androgens. Inadequate production of progesterone in the luteal phase may set the stage for RPL.
A controversial area is the presence of increased natural killer cells in the uterus. It is poorly understood whether these cells actually inhibit the formation of a placenta, and it has been noted that they might be essential for this process. A 2004 paper (Moffett et al) warned that determination of NK cells in peripheral blood does not predict uterine NK cell numbers, because they are a different class of lymphocytes, and state that immunosuppression|immunosuppressive treatments are not warranted.
Antiphospholipid syndrome is also implicated.
The risk for miscarriage increases with age, and women in the advanced reproductive age are prone to higher risk of repeated msicarriages. Such miscarriages are due to decreased egg quality.
While an infection can lead to a single pregnancy loss, there are no confirmed studies to suggest that specific infections will lead to recurrent pregnancy loss in humans.
Parental HLA sharing
Earlier studies that perhaps paternal sharing of HLA genes would be associated with increased pregnancy loss have not been confirmed.
While lifestyle factors have been associated with increased risk for miscarriage in general, and are usually not listed as specific causes for RPL, every effort should be made to address these issues in patients with RPL.
Transvaginal ultrasonography has become the primary method of assessment of the health of an early pregnancy. Blood tests for thrombophilia and thyroid function and a karyogram are performed.
Christiansen OB, et al: Evidence-based investigations and treatments of recurrent pregnancy loss. Fertil Steril 2005;83:821-9.
Moffett A, Regan L, Braude P. Natural killer cells, miscarriage, and infertility. British Medical Journal|BMJ 2004;329:1283-5. PMID 15564263.
note|RCOG2003 Royal College of Obstetricians and Gynaecologists – The Investigation and Treatment of Couple with Recurrent Miscarriage Guideline No 17 http://www.rcog.org.uk/resources/Public/pdf/Recurrent_Miscarriage_No17.pdf PDF document
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article “Habitual abortion”.