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Habitual abortion
Habitual abortion or recurrent pregnancy loss (RPL) is the occurrence of repeated pregnanciesthat end in miscarriageof the fetus, usually before 20 weeks of gestation. RPL affects about 0.34%[{{fullurl:Template:FULLPAGENAME}}#endnote_RCOG2003] of women who conceive.
DefinitionHabitual 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%[{{fullurl:Template:FULLPAGENAME}}#endnote_RCOG2003] is regarded as "habitual". CausesThere are various causes for habitual abortions, and some are treatable. Some couples never have a cause identified, often after extensive investigations.[{{fullurl:Template:FULLPAGENAME}}#endnote_RCOG2003] Uterine conditionsAn uterine malformationis 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 leiomyomatacould result to pregnancy loss. In the second trimester a weak cervixcan become a recurrent problem. ThrombophiliaAn important example is the increased risk of abortion in women with thrombophilia(propensity for blood clots). Recent studies confirm that anticoagulantmedication may improve the chances of carrying pregnancy to term. It explains about 15% of recurrent miscarriages. TranslocationsA balanced translocationor Robertsonian translocationin one of the partners leads to unviable fetuses that are aborted spontaneously. This explains why a karyogramis 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. Endocrine disordersWomen with thyroiddisorders, both hypo- or hyperactivity, have are at increased risk for pregnancy losses. Unrecognized or poorly treated diabetes mellitusleads to increased miscarriages. Women with polycystic ovary syndromealso have higher loss rates possibly related to hyperinsulinemia or excess androgens. Inadequate production of progesteronein the luteal phase may set the stage for RPL. Immune factorsA controversial area is the presence of increased natural killer cellsin 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 immunosuppressivetreatments are not warranted. Antiphospholipid syndromeis also implicated. Ovarian ageThe 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. InfectionWhile 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 sharingEarlier studies that perhaps paternal sharing of HLAgenes would be associated with increased pregnancy loss have not been confirmed. Lifestyle factorsWhile 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. AssessmentTransvaginal ultrasonographyhas become the primary method of assessment of the health of an early pregnancy. Blood testsfor thrombophiliaand thyroidfunction and a karyogramare performed. References
Categories: Fertility medicine| Obstetrics
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