Abnormal Uterus and Miscarriage Risk

Common Concerns About Uterine Shape and Structure

An abnormal uterus can sometimes be a risk factor for miscarriage and, in some cases, a cause of recurrent miscarriages. Some uterine malformations are present from birth, and others develop during adulthood. Only some types of uterine malformations increase the risk of miscarriage and require treatment; others may not cause any problems with pregnancy at all.

Diagnosis of congenital uterine malformations usually comes after a hysteroscopy or hysterosalpingogram.

Uterine Septum

A uterine septum (septate uterus) is the most common congenital uterine malformation. It is a band of tissue partially dividing the uterus, usually without a good blood supply. If a fertilized egg implants on the septum, miscarriage is likely. Treatment is usually minor surgery. A septate uterus is present from before a woman's own birth.

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Bicornuate Uterus

A bicornuate uterus is a heart-shaped uterus, which is a type of congenital malformation (present from birth). Most women with a bicornuate uterus do not have complications, but in some, a bicornuate uterus can lead to increased risk of preterm labor. A bicornuate uterus is not believed to increase risk of first-trimester miscarriage.

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Unicornuate Uterus

A unicornuate uterus is a horn-shaped uterus. It is a congenital malformation in which one side of the uterus does not develop properly. A unicornuate uterus increases risk of ectopic pregnancy, miscarriage, and preterm delivery.

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Didelphic Uterus

A didelphic uterus is a "double" uterus, and studies have found that it may increase the risk of preterm delivery and possibly of miscarriage. Didelphic uterus is present from birth.

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T-Shaped Uterus or DES Exposure

A T-shaped uterus is another type of congenital malformation of the uterus that is associated with recurrent miscarriages and increased risk of preterm labor. Some women who have a T-shaped uterus do not experience problems, while others do. This specific malformation is sometimes found in women whose mothers took a drug called DES, which was prescribed to some women in the 1960s and 1970s. DES can also cause increased risk of other pregnancy problems.

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Cervical Insufficiency

Cervical insufficiency, or incompetent cervix, means that a woman's cervix begins to dilate too early in pregnancy -- resulting in preterm delivery and sometimes second-trimester pregnancy loss. Cervical insufficiency is not a factor in first-trimester miscarriage. It can be related to congenital malformations or may develop during adulthood.

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Many women have uterine fibroids, but some types of fibroids can cause miscarriage or other pregnancy complications. Fibroids can develop during adulthood.

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Tipped Uterus

Many women are concerned to hear that they have a tipped (retroverted) uterus, but there is no evidence that a tipped uterus increases the risk of miscarriage or any other problems in pregnancy.

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