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.

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 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.

True cervical pregnancies tend to abort; if, however, the pregnancy is located higher in the canal and the placenta finds support in the uterine cavity it can go past the first trimester. With the placenta being implanted abnormally extensive vaginal bleeding can be expected at time of delivery and placental removal. While early cervical pregnancies may abort spontaneously or can be managed with excision, D&C, suturing, electrocautery, and tamponading, by medication such as methotrexate, and/or by uterine artery embolization, a more advanced pregnancy may require a hysterectomy to control bleeding. The more advanced the pregnancy the higher the risk for a major bleeding necessitating a hysterectomy.

On a very rare occasion, a cervical pregnancy results in the birth of a live baby, typically the pregnancy is in the upper part of the cervical canal and manages to extend into the lower part of the uterine cavity.

A cervical pregnancy can develop together with a normal intrauterine pregnancy; such a heterotopic pregnancy will call for expert management as to not to endanger the intrauterine pregnancy.

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%).

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.

Cervical agenesis is estimated to occur in 1 in 80,000 females. It is often associated with deformity of the vagina; one study found that 48% of patients with cervical agenesis had a normal, functional vagina, while the rest of the cases were accompanied by vaginal hypoplasia.

The condition may not be known to the affected individual and not result in any reproductive problems; thus normal pregnancies may occur. However, it is associated with a higher risk for miscarriage, premature birth, and malpresentation. According to the classical study by Buttram there is a 60% risk of a spontaneous abortion, this being more common in the second than in the first trimester. However, there is no agreement on this number and other studies show a lower risk. Woelfer found that the miscarriage risk is more pronounced in the first trimester.

The condition is also associated with abnormalities of the renal system. Further, skeletal abnormalities have been linked to the condition.

Over one million cases of acute salpingitis are reported every year in the US, but the number of incidents is probably larger, due to incomplete and untimely reporting methods and that many cases are reported first when the illness has gone so far that it has developed chronic complications. For women age 16–25, salpingitis is the most common serious infection. It affects approximately 11% of females of reproductive age.

Salpingitis has a higher incidence among members of lower socioeconomic classes. However, this is thought of being an effect of earlier sex debut, multiple partners, and decreased ability to receive proper health care rather than any independent risk factor for salpingitis.

As an effect of an increased risk due to multiple partners, the prevalence of salpingitis is highest for people age 15–24 years. Decreased awareness of symptoms and less will to use contraceptives are also common in this group, raising the occurrence of salpingitis.

The incidence has been reported to be about 1:1,000 to 1: 16,000 pregnancies.

Pregnancies involving the isthmus - the segment of the uterus between the cervix and the fundus - are more common than true cervical pregnancies. While in many situations the cause of the abnormal implantation remains unclear, there is evidence to link the development of cervical pregnancy to uterine instrumentation, specifically repeated D&Cs (dilatation and curettage). Cervical pregnancies are to be distinguished from pregnancies that start from an implantation in a scar of a previous cesarean section, so-called "scar pregnancies".

For the affected, 20% need hospitalization.

Regarding patients age 15–44 years, 0.29 per 100,000 dies from salpingitis.

However, salpingitis can also lead to infertility because the eggs released in ovulation can't get contact with the sperm. Approximately 75,000-225,000 cases of infertility in the US are caused by salpingitis. The more times one has the infection, the greater the risk of infertility. With one episode of salpingitis, the risk of infertility is 8-17%. With 3 episodes of salpingitis, the risk is 40-60%, although the exact risk depends on the severity of each episode.

In addition, damaged oviducts increase the risk of ectopic pregnancy. Thus, if one has had salpingitis, the risk of a pregnancy to become ectopic is 7 to 10-fold as large. Half of ectopic pregnancies are due to a salpingitis infection.

Other complications are:

- Infection of ovaries and uterus

- Infection of sex partners

- An abscess on the ovary

Cervical stenosis may impact natural fertility by impeding the passage of semen into the uterus. In the context of infertility treatments, cervical stenosis may complicate or prevent the use of intrauterine insemination (IUI) or in vitro fertilization (IVF) procedures.

Cervical stenosis may be present from birth or may be caused by other factors:

- Surgical procedures performed on the cervix such as colposcopy, cone biopsy, or a cryosurgery procedure

- Trauma to the cervix

- Repeated vaginal infections

- Atrophy of the cervix after menopause

- Cervical cancer

- Radiation

- Cervical nabothian cysts

Hematometra develops when the uterus becomes distended with blood secondary to obstruction or atresia of the lower reproductive tract—the uterus, cervix or vagina—which would otherwise provide an outflow for menstrual blood. It is most commonly caused by congenital abnormalities, including imperforate hymen, transverse vaginal septum or vaginal hypoplasia. Other causes are acquired, such as cervical stenosis, intrauterine adhesions, endometrial cancer, and cervical cancer.

Additionally, hematometra may develop as a complication of uterine or cervical surgery such as endometrial ablation, where scar tissue in the endometrium can "wall off" sections of endometrial glands and stroma causing blood to accumulate in the uterine cavity. It can also develop after abortion, as well as after childbirth. It can also develop after female genital mutilation.

The following have been identified as risk factors for placenta previa:

- Previous placenta previa (recurrence rate 4–8%), caesarean delivery, myomectomy or endometrium damage caused by D&C.

- Women who are younger than 20 are at higher risk and women older than 35 are at increasing risk as they get older.

- Alcohol use during pregnancy was previous listed as a risk factor, but is discredited by this article.

- Women who have had previous pregnancies ( multiparity ), especially a large number of closely spaced pregnancies, are at higher risk due to uterine damage.

- Smoking during pregnancy; cocaine use during pregnancy

- Women with a large placentae from twins or erythroblastosis are at higher risk.

- Race is a controversial risk factor, with some studies finding that people from Asia and Africa are at higher risk and others finding no difference.

- Placental pathology (Vellamentous insertion, succinturiate lobes, bipartite i.e. bilobed placenta etc.)

- Baby is in an unusual position: breech (buttocks first) or transverse (lying horizontally across the womb).

Placenta previa is itself a risk factor of placenta accreta.

A uterine malformation is a type of female genital malformation resulting from an abnormal development of the Müllerian duct(s) during embryogenesis. Symptoms range from amenorrhea, infertility, recurrent pregnancy loss, and pain, to normal functioning depending on the nature of the defect.

A vaginal septum is a congenital partition within the vagina; such a septum could be either longitudinal or transverse.

If untreated, the accumulation of menstrual fluid in the uterus caused by cervical agenesis can lead to hematocolpos, hematosalpinx, endometriosis, endometrioma and pelvic adhesions.

The risk of developing pyometra differs between dog breeds. Pyometra is a result of hormonal and structural changes in the uterus lining. This can happen at "any" age, whether she has bred or not, and whether it is her 1st or 10th heat (although it becomes more common as the dog gets older). The main risk period for a female is for eight weeks after her peak standing heat (or estrous cycle) has ended. Normally during this period, the cervix, which was open during her heat, begins to close, and the inner lining begins to adapt back to normal. However, cystic hyperplasia of the endometrium (inner lining of the uterus) – known as cystic endometrial hyperplasia (CEH) – may occur at this time for some animals, as an inappropriate response to progesterone.

Under these circumstances, bacteria (especially "E. coli") that have migrated from the vagina into the uterus find the environment favorable to growth, especially since progesterone also causes mucus secretion, closes the cervix (preventing uterine drainage), and decreases uterine contractility. The condition of the cervix is a major factor in the severity of the condition.

Hematometra or hemometra is a medical condition involving collection or retention of blood in the uterus. It is most commonly caused by an imperforate hymen or a transverse vaginal septum.

Endometrial polyps usually occur in women in their 40s and 50s. Endometrial polyps occur in up to 10% of women. It is estimated that they are present in 25% of women with abnormal vaginal bleeding.

Females that have received estradiol as a mismating shot (abortifacient) in diestrus are at risk for more severe disease because estrogen increases the number of progesterone receptors in the endometrium. 25 percent of females receiving estradiol in diestrus develop pyometra. Pyometra is less common in female cats because progesterone is only released by the ovaries after mating. Also in cats, the risk of developing the disease differ depending on breed.