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Causes
By Mayo Clinic staffA molar pregnancy is caused by an abnormally fertilized egg. Human cells normally contain 23 pairs of chromosomes. One chromosome in each pair comes from the father, the other from the mother. In a complete molar pregnancy, all of the fertilized egg's chromosomes come from the father. Shortly after fertilization, the chromosomes from the mother's egg are lost or inactivated and the father's chromosomes are duplicated. The egg may have had an inactive nucleus or no nucleus.
In a partial or incomplete molar pregnancy, the mother's chromosomes remain but the father provides two sets of chromosomes. As a result, the embryo has 69 chromosomes, instead of 46. This can happen when the father's chromosomes are duplicated or if two sperm fertilize a single egg.
- Early pregnancy loss: Miscarriage and molar pregnancy. American College of Obstetricians and Gynecologists. http://www.acog.org/publications/patient_education/bp090.cfm. Accessed Aug. 14, 2009.
- Ectopic and molar pregnancy. March of Dimes. http://www.marchofdimes.com/professionals/14332_1189.asp. Accessed Aug. 14, 2009.
- Copeland LJ, et al. Malignant diseases in pregnancy. In: Gabbe SG, et al. Obstetrics: Normal and Problem Pregnancies. 5th ed. Philadelphia, Pa.: Elsevier Churchill Livingstone; 2007:1.
- Garner EIO. Gestational trophoblastic disease: Management of hydatidiform mole. http://www.uptodate.com/home/index.html. Accessed Aug. 17, 2009.
- Berek JS. Gestational trophoblastic disease: Pathology. http://www.uptodate.com/home/index.html. Accessed Aug. 17, 2009.
- Chang JW, et al. Gestational trophoblastic disease: Epidemiology, clinical manifestations and diagnosis. http://www.uptodate.com/home/index.html. Accessed Aug. 17, 2009.
- Garner EIO. Malignant gestational trophoblastic disease: Staging and treatment. http://www.uptodate.com/home/index.html. Accessed Aug. 17, 2009.
- Kavanagh JJ, et al. Comprehensive gynecology. Gestational trophoblastic disease: Hydatidiform mole, nonmetastatic and metastatic gestational trophoblastic tumor — Diagnosis and management. In: Katz VL, et al. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:1.
- Dilation and curettage. American College of Obstetricians and Gynecologists. http://www.acog.org/publications/patient_education/bp062.cfm. Accessed Aug. 18, 2009.
- Al-Hussaini TK, et al. Recurrent pregnancy loss due to familial and non-familial habitual molar pregnancy. International Journal of Gynecology and Obstetrics. 2003;83:179.
- Harms RW (expert opinion). Mayo Clinic, Rochester, Minn. Sept. 16, 2009.
