The occurrence of all types of paramesonephric duct abnormalities in women is estimated around 0.4%.

A bicornuate uterus is estimated to occur in 0.1-0.5% of women in the U.S.

It is possible that this figure is an underestimate, since subtle abnormalities often go undetected. Some intersex individuals whose external genitalia are perceived as being male may nonetheless have a variably shaped uterus.

In the United States, uterus didelphys is reported to occur in 0.1–0.5% of women. It is difficult to know the exact occurrence of this anomaly, as it may go undetected in the absence of medical and reproductive complications.

Pregnancies in a bicornuate uterus are usually considered high risk and require extra monitoring because of association with poor reproduction potential.

A bicornuate uterus is associated with increased adverse reproductive outcomes, such as:

- Recurrent pregnancy loss

- Preterm birth: The rate of preterm delivery is 15 to 25%. A pregnancy may not reach full term in a bicornuate uterus when the baby begins to grow in either of the uterine horns. A short cervical length seems to be a good predictor of preterm delivery in women with a bicornuate uterus.

- Malpresentation (breech birth or transverse presentation): a breech presentation occurs in 40-50% of pregnancies with a partial bicornuate uterus and not at all (0%) in a complete bicornuate uterus.

- Deformity: Offspring of mothers with a bicornuate uterus are at high risk for "deformities and disruptions" and "malformations."

Previously, a bicornuate uterus was thought to be associated with infertility, but recent studies have not confirmed such an association.

AS has a reported incidence of 25% of D&Cs performed 1–4 weeks post-partum, up to 30.9% of D&Cs performed for missed miscarriages and 6.4% of D&Cs performed for incomplete miscarriages. In another study, 40% of patients who underwent repeated D&C for retained products of conception after missed miscarriage or retained placenta developed AS.

In the case of missed miscarriages, the time period between fetal demise and curettage may increase the likelihood of adhesion formation due to fibroblastic activity of the remaining tissue.

The risk of AS also increases with the number of procedures: one study estimated the risk to be 16% after one D&C and 32% after 3 or more D&Cs. However, a single curettage often underlies the condition.

In an attempts to estimate the prevalence of AS in the general population, it was found in 1.5% of women undergoing hysterosalpingography HSG, and between 5 and 39% of women with recurrent miscarriage.

After miscarriage, a review estimated the prevalence of AS to be approximately 20% (95% confidence interval: 13% to 28%).

A number of twin gestations have occurred where each uterus carried its pregnancy separately. A recent example occurred on February 26, 2009, when Sarah Reinfelder of Sault Ste. Marie, Michigan delivered two healthy, although seven weeks premature, infants by cesarean section at Marquette General Hospital. It is possible that the deliveries occur at different times, thus the delivery interval could be days or even weeks.

The extent of adhesion formation is critical. Mild to moderate adhesions can usually be treated with success. Extensive obliteration of the uterine cavity or fallopian tube openings (ostia) and deep endometrial or myometrial trauma may require several surgical interventions and/or hormone therapy or even be uncorrectable. If the uterine cavity is adhesion free but the ostia remain obliterated, IVF remains an option. If the uterus has been irreparably damaged, surrogacy or adoption may be the only options.

Depending on the degree of severity, AS may result in infertility, repeated miscarriages, pain from trapped blood, and future obstetric complications If left untreated, the obstruction of menstrual flow resulting from adhesions can lead to endometriosis in some cases.

Patients who carry a pregnancy even after treatment of IUA may have an increased risk of having abnormal placentation including placenta accreta where the placenta invades the uterus more deeply, leading to complications in placental separation after delivery. Premature delivery, second-trimester pregnancy loss, and uterine rupture are other reported complications. They may also develop incompetent cervix where the cervix can no longer support the growing weight of the fetus, the pressure causes the placenta to rupture and the mother goes into premature labour. Cerclage is a surgical stitch which helps support the cervix if needed.

Pregnancy and live birth rate has been reported to be related to the initial severity of the adhesions with 93, 78, and 57% pregnancies achieved after treatment of mild, moderate and severe adhesions, respectively and resulting in 81, 66, and 32% live birth rates, respectively. The overall pregnancy rate after adhesiolysis was 60% and the live birth rate was 38.9% according to one study.

Age is another factor contributing to fertility outcomes after treatment of AS. For women under 35 years of age treated for severe adhesions, pregnancy rates were 66.6% compared to 23.5% in women older than 35.

Most studies of uterine malformations are based on populations of women who have experienced a pregnancy loss and thus do not address the issue of the prevalence in the general population. A screening study by Woelfer et al. of women without a history of reproductive problems found that about 5% of women had an arcuate uterus when they defined an arcuate uterus any fundal protrusion into the cavity that had an apical angle of more than 90 degrees. Accordingly, it was the most common uterine anomaly, followed by septate uterus (3%) and bicornuate uterus (0.5%).

Fertility following ectopic pregnancy depends upon several factors, the most important of which is a prior history of infertility. The treatment choice does not play a major role; A randomized study in 2013 concluded that the rates of intrauterine pregnancy 2 years after treatment of ectopic pregnancy are approximately 64% with radical surgery, 67% with medication, and 70% with conservative surgery. In comparison, the cumulative pregnancy rate of women under 40 years of age in the general population over 2 years is over 90%.

The condition may not be known to the affected individual and not result in any reproductive problems; thus normal pregnancies occur. Indeed, there is no consensus on the relationship of the arcuate uterus and recurrent pregnancy loss. Accordingly, the condition may be a variation or a pathology.

One view maintains that the condition is associated with a higher risk for miscarriage, premature birth, and malpresentation. Thus a study that evaluated women with uterine bleeding by hysteroscopy found that 6.5% of subjects displayed the arcuate uterus and had evidence of reproductive impairments. A study based on hysterosalpingraphic detected arcuate lesions documented increased fetal loss and obstetrical complications as a risk for affected women. Woelfer found that the miscarriage risk is more pronounced in the second trimester. In contrast, a study utilizing 3-D ultrasonography to document the prevalence of the arcuate uterus in a gynecological population found no evidence of increased risk of reproductive loss; in this study 3.1% of women had an arcuate uterus making it the most common uterine anomaly; this prevalence was similar than in women undergoing sterilization and lower than in women with recurrent pregnancy loss.

When ectopic pregnancies are treated, the prognosis for the mother is very good in Western countries; maternal death is rare, but most fetuses die or are aborted. For instance, in the UK, between 2003 and 2005 there were 32,100 ectopic pregnancies resulting in 10 maternal deaths (meaning that 1 in 3,210 women with an ectopic pregnancy died).

In the developing world, however, especially in Africa, the death rate is very high, and ectopic pregnancies are a major cause of death among women of childbearing age.

Interstitial pregnancies account for 2–4% of all tubal pregnancies, or for 1 in 2,500 to 5,000 live births. About one in fifty women with an interstitial pregnancy dies. Patients with an interstitial pregnancies have a 7-times higher mortality than those with ectopics in general. With the growing use of assisted reproductive technologies, the incidence of interstitial pregnancy is rising.

Most studies are based on populations of women who have experienced a pregnancy loss and thus do not address the issue of the prevalence in the general population. A screening study by Woelfer et al. of women without a history of reproductive problems found that about 3% of women had a uterine septation; the most common anomaly in their study was an arcuate uterus (5%), while 0.5% were found to have a bicornuate uterus. In contrast, in about 15% of patients with recurrent pregnancy loss anatomical problems are thought to be causative with the septate uterus as the most common finding.

Women with the condition may be asymptomatic and unaware of having a uniconuate uterus; normal pregnancy may occur. In a review of the literature Reichman et al. analyzed the data on pregnancy outcome of 290 women with a unicornuate uterus. 175 women had conceived for a total of 468 pregnancies. They found that about 50% of patients delivered a live baby. The rates for ectopic pregnancy was 2.7%, for miscarriage 34%, and for preterm delivery 20%, while the intrauterine demise rate was 10%. Thus patients with a unicornuate uterus are at a higher risk for pregnancy loss and obstetrical complications.

The prevalence of uterine malformation is estimated to be 6.7% in the general population, slightly higher (7.3%) in the infertility population, and significantly higher in a population of women with a history of recurrent miscarriages (16%).

Diets high in fruits and vegetables tend to lower the risk of developing fibroids. Fruits, especially citrus, have a greater protective benefit than vegetables. Normal dietary levels of vitamin D is shown to reduce the risk of developing fibroids. No protective benefit has been found with the consumption of folate, whole grains, soy products, or fiber. No association between the consumption of fat, eggs, dairy products has been shown to increase the risk of fibroids.

The uterus is normally formed during embryogenesis by the fusion of the two Müllerian ducts. If one of the ducts does not develop, only one Müllerian duct contributes to the uterine development. This uterus may or may not be connected to Müllerian structure on the opposite site if the Müllerian duct on that site undergoes some development. A unicornuate uterus has a single cervix and vagina.

Associated defects may affect the renal system, and less common, the skeleton.

The condition is much less common than these other uterine malformations: arcuate uterus, septate uterus, and bicornuate uterus. While the uterus didelphys is estimated to occur in 1/3,000 women, the unicornuate uterus appears to be even more infrequent with an estimated occurrence of about 1/4,000.

A uterine scar from a previous cesarean section is the most common risk factor. (In one review, 52% had previous cesarean scars.) Other forms of uterine surgery that result in full-thickness incisions (such as a myomectomy), dysfunctional labor, labor augmentation by oxytocin or prostaglandins, and high parity may also set the stage for uterine rupture. In 2006, an extremely rare case of uterine rupture in a first pregnancy with no risk factors was reported.

The cause of this condition is not completely understood. Potential risk factors may include defects in the egg, abnormalities within the uterus, or nutritional deficiencies. Women under 20 or over 40 years of age have a higher risk. Other risk factors include diets low in protein, folic acid, and carotene. The diploid set of sperm-only DNA means that all chromosomes have sperm-patterned methylation suppression of genes. This leads to overgrowth of the syncytiotrophoblast whereas dual egg-patterned methylation leads to a devotion of resources to the embryo, with an underdeveloped syncytiotrophoblast. This is considered to be the result of evolutionary competition with male genes driving for high investment into the fetus versus female genes driving for resource restriction to maximise the number of children.

Because pregnancy is outside the uterus, abdominal pregnancy serves as a model of human male pregnancy or for females who lack a uterus, although such pregnancy would be dangerous.

Cases of combined simultaneous abdominal and intrauterine pregnancy have been reported.

About 1.4% of ectopic pregnancies are abdominal, or about 1 out of every 8,000 pregnancies. A report from Nigeria places the frequency in that country at 34 per 100,000 deliveries and a report from Zimbabwe, 11 per 100,000 deliveries. The maternal mortality rate is estimated to be about 5 per 1,000 cases, about seven times the rate for ectopics in general, and about 90 times the rate for a "normal" delivery (1987 US data).

Patients with an ectopic pregnancy are generally at higher risk for a recurrence, however, there are no specific data for patients with an interstitial pregnancy. When a new pregnancy is diagnosed it is important to monitor the pregnancy by transvaginal sonography to assure that is it properly located, and that the surgically repaired area remains intact. Cesarean delivery is recommended to avoid uterine rupture during labor.

Emergency exploratory laparotomy with cesarean delivery accompanied by fluid and blood transfusion are indicated for the management of uterine rupture. Depending on the nature of the rupture and the condition of the patient, the uterus may be either repaired or removed (cesarean hysterectomy). Delay in management places both mother and child at significant risk.

More than 80% of hydatidiform moles are benign. The outcome after treatment is usually excellent. Close follow-up is essential. Highly effective means of contraception are recommended to avoid pregnancy for at least 6 to 12 months.

In 10 to 15% of cases, hydatidiform moles may develop into invasive moles. This condition is named "persistent trophoblastic disease" (PTD). The moles may intrude so far into the uterine wall that hemorrhage or other complications develop. It is for this reason that a post-operative full abdominal and chest x-ray will often be requested.

In 2 to 3% of cases, hydatidiform moles may develop into choriocarcinoma, which is a malignant, rapidly growing, and metastatic (spreading) form of cancer. Despite these factors which normally indicate a poor prognosis, the rate of cure after treatment with chemotherapy is high.

Over 90% of women with malignant, non-spreading cancer are able to survive and retain their ability to conceive and bear children. In those with metastatic (spreading) cancer, remission remains at 75 to 85%, although their childbearing ability is usually lost.

Adenomyosis is a benign but often progressing condition. It is advocated that adenomyosis poses no increased risk for cancer development. However, both entities could coexist and the endometrial tissue within the myometrium could harbor endometrioid adenocarcinoma, with potentially deep myometrial invasion. As the condition is estrogen-dependent, menopause presents a natural cure. Ultrasound features of adenomyosis will still be present after menopause. People with adenomyosis are also more likely to have uterine fibroids or endometriosis.

Adenomyosis itself can cause infertility issues, however, fertility can be improved if the adenomyosis has resolved following hormone therapies like levonorgestrel therapy. The discontinuation of medication or removal of IUD can be timed to be coordinated with fertility treatments. There has also been one report of a successful pregnancy and healthy birth following high-frequency ultrasound ablation of adenomyosis.

Preterm labour and premature rupture of membranes both occur more frequently in women with adenomyosis.

In sub-fertile women who received in-vitro fertilization (IVF), women with adenomyosis were less likely to become pregnant and subsequently more likely to experience a miscarriage. Given this, it is encouraged to screen women for adenomyosis by TVUS or MRI before starting assisted reproduction treatments (ART).